Prince of Preachers, Charles. H. Spurgeon said:
“the proper study of God’s elect is God; the proper study of a Christian is the Godhead. The highest science, the loftiest speculation, the mightiest philosophy, which can ever engage the attention of a child of God, is the name, the nature, the person, the work, the doings, and the existence of the great God whom he calls his Father. There is something exceedingly improving to the mind in a contemplation of the Divinity.”
Here is a definition of the Doctrine of the Trinity:
The three Biblical doctrines that flow directly into the river that is the Trinity are as follows:
1) There is one and only one God, eternal, immutable.
2) There are three eternal Persons described in Scripture – the Father, the Son, and the Spirit. These Persons are never identified with one another – that is, they are carefully differentiated as Persons.
3) The Father, the Son, and the Spirit, are identified as being fully deity—that is, the Bible teaches the Deity of Christ and the Deity of the Holy Spirit.
A close friend, Dr James White notes;
“We are not saying that the Father is the Son, or the Son the Spirit, or the Spirit the Father. It is very common for people to misunderstand the doctrine as to mean that we are saying Jesus is the Father. The doctrine of the Trinity does not in any way say this!”
Christians affirm specifically line four in the Athanasian Creed “that we worship one God in Trinity, and the Trinity in unity. Neither confounding the Persons nor dividing the Substance.” So what was the Jewish understanding of “plurality and unity” before the first three centuries.
Old Testament unity and plurality:
We are familiar with the Shema (Obey) in Deuteronomy 6:4 that stipulate the uniqueness of devotion necessarily rendered to the One God of Israel. It reads: “Hear O Israel the Lord your God, the Lord is One [echad].” [Sh’ma Yisrael Adonai Eloheinu Adonai Ecḥad.”]. What is the ‘One’?
Michael Brown wrote:
“Actually, ‘echad simply means ‘one,’ exactly like our English word ‘one.’ While it can refer to compound unity (just as our English word can, as in one team, one couple, etc.), it does not specifically refer to compound unity. On the other hand, ‘echad certainly does not refer to the concept of absolute unity, an idea expressed most clearly in the twelfth century by Moses Maimonides, who asserted that the Jewish people must believe that God is yachid, an ‘only’ one. There is no doubt that this reaction was due to exaggerated, unbiblical, ‘Christian’ beliefs that gave Jews the impression Christians worshiped three gods.”
As Israeli Scholar Yehezkel Kaufmann shows clearly, Israel was more concerned with a polemic against idolatry that would exclude other Gods in light of YWHWs superiority than the numeric understanding of the One God. God is One”
I have written extensively on the intention of the Jewish Shema in my article ‘The Shema ‘Yisrael reviewed’ on this site and have shown extensively that the primary concern of this confession was to emphasise the devotion to the One God. New Testament Scholar N.T.Wright agrees and adds:
“about the nature and variety of early Jewish monotheism… we have very few examples of ‘pure’ [unipersonalism] monotheism anywhere, including in the Hebrew Bible… there is no suggestion that ‘monotheism’, or praying the Shema, had anything to do with the numerical analysis of the inner being of Israel’s god Himself… we find strong evidence during this period of Jewish groups and individuals who, speculating on the meaning of some difficult passages of Scripture (Dan7; Gen 1) suggested that the Divine being might encompass a plurality…but none of these show any awareness that they are transgressing normal Jewish monotheism.” “Jewish-style … Monotheism was never, in our period, an inner analysis of the inner being of the One God. It was always a way of saying, frequently at great risk: our God is the true God, and your gods are worthless idols. It was a way of holding onto hope.”
Jewish Scholar Nahum Sarna affirms that:
“From several texts, it is clear that the demarcation between God and His angel is often blurred [Gen.16:7-9, 11, 15-18; Exod.3:2, 4; Judg.6:11-23] at the Exodus from Egypt it is now God [Exod.13:21]; now His angel [Exod.14:9] goes ahead of the Israelite camp.” 
It is simply not a foreign concept in the Old Testament that we can identify both a plurality and a unity in the One God of Israel.
The Prophet Isaiah (63:9-16) mention:
“In all their suffering, He suffered, and the Angel of His Presence saved them (ANGEL OF YHWH identified as YHWH). He redeemed them because of His love and compassion; He lifted them up and carried them all the days of the past. 10 But they rebelled and grieved His Holy Spirit (SPIRIT OF YHWH). So He became their enemy and fought against them. 11 Then He remembered the days of the past, the days of Moses and his people. Where is He who brought them out of the sea with the shepherds of His flock? Where is He who put His Holy Spirit among the flock? 12 He sent His glorious arm to be at Moses’ right hand, divided the waters before them to obtain eternal fame for Himself,13 and led them through the depths like a horse in the wilderness, so that they did not stumble. 14 Like cattle that go down into the valley, the Spirit of the Lord gave them rest. You led Your people this way to make a glorious name for Yourself. 15 Look down from heaven and see from Your lofty home—holy and beautiful. Where is Your zeal and Your might? Your yearning[i] and Your compassion are withheld from me. 16 Yet You are our Father, even though Abraham does not know us and Israel doesn’t recognize us. You, Yahweh, are our Father; from ancient times, Your name is our Redeemer.”
After investigating this reality in the Old Testament Jewish Scholar Benjamin Summer in his podcast ‘The bodies of God and the ancient world of Israel’ Part 4 says:
“When the New Testament talks about Jesus as being some sort of small scale human manifestation of God, that really sounds to Jews so utterly pagan, but what I’m suggesting is perhaps the radical idea for us Jews–that in fact, it’s not so pagan…We Jews have always tended to sort of make fun of the Trinity…[that Christians] aren’t real monotheists like we Jews are or like the Muslims are, but I think what we have been seeing from what I’ve been saying for the past couple of days [is] the idea of the Trinity…[is] actually an old ancient Near Eastern idea…that can also function in a monotheistic context, … we Jews have no theological objection to the doctrine of the Trinity…The Trinity is an old Ancient Near Eastern idea that shows up in the Tanakh and in a different way shows up in Jewish mysticism as well.” 
Rabbi Eliezer Hakkalir (c.570 – c.640) was a Byzantine Jew and Hebrew poet exclaimed, “There are ‘Three’, but each exists by Himself.” The idea that the God of the Old Testament was ‘triplex’ is what the New Testament authors and the First Church Fathers saw! So what about the Trinity in the first three centuries?
The Catholic Encyclopedia mentions,
“The early Fathers were persuaded that indications of the doctrine of the Trinity must exist in the Old Testament and they found such indications in not a few passages. Many of them not merely believed that the Prophets [in the Old Testament] had testified of it, they held that it had been made known even to the Patriarchs. … The matter seems to be correctly summed up by Epiphanius, when he says: “The One Godhead is above all declared by Moses, and the twofold personality (of Father and Son) is strenuously asserted by the Prophets. The Trinity is made known by the Gospel.”
Apostolic Age (New Testament):
The Gospel authors depict a reality in which Jesus is emphatically identified as Godf.
John 1:1 the Beloved Disciple says; “In the beginning was the Word, and the Word was with God, and the Word was God.” John identifies later in the same Gospel (14:17 & 26) that the reality that the knowledge of the One God determines the association of the three distinct persons. He writes: “But you do know Him (Holy Spirit), because He remains with you and will be in you…But the Counselor, the Holy Spirit—the Father will send Him in My name—will teach you all things and remind you of everything I (Jesus) have told you.”
There is simply no doubt that Father, Son, and Holy Spirit is essential for the full relational understanding of the One God. In Acts (1:2, 4-5) Luke the Physician writes: “until the day He (Jesus) was taken up, after He had given orders through the Holy Spirit to the apostles He had chosen. While He was together with them, He commanded them not to leave Jerusalem, but to wait for the Father’s promise. “This,” He said, “is what you heard from Me; for John baptized with water, but you will be baptized with the Holy Spirit not many days from now.”
There is a clear revelation of the three, yet, nowhere in the First Christian community is there any mention of a violation of God’s essential Unity, or a denial of His complexity as Father, Son, and Holy Spirit. Luke adds that the very sermon the Apostle Peter preached to the men of Israel was that: “since He (Jesus) has been exalted to the right hand of God and has received from the Father the promised Holy Spirit, He has poured out what you both see and hear” (Acts 2:33). The Gospel authors clearly included both the Son, Jesus Christ, and the Holy Spirit, in the revelation, identity, and working of the one God of Israel.
So what about the Apostle Paul? Paul the Apostle also affirms both the Son, and the Holy Spirit, in the revelation, identity, and working of the one God of Israel. He writes to the Galatian Church (4:4-7) “When the time came to completion, God sent His Son, born of a woman, born under the law, to redeem those under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of His Son into our hearts, crying, “Abba, Father!” So you are no longer a slave but a son, and if a son, then an heir through God.’ He also wrote to the Ephesian Church (4:4-6)”There is one body and one Spirit—just as you were called to one hope at your calling— one Lord, one faith, one baptism, one God and Father of all, who is above all and through all and in all.” Paul writes to the young Titus (3:4-6) “But when the kindness of GodourSavior and His love for mankind appeared, He saved us— not by works of righteousness that we had done, but according to His mercy, through the washing of regeneration and renewal by the Holy Spirit. He poured out this Spirit on us abundantly through JesusChrist our Savior.” When it comes to the distribution of the gifts within the first Christian community, Paul writes to the Corinthians (12:4-6): “Now there are different gifts, but the same Spirit. There are different ministries, but the same Lord (Jesus). And there are different activities, but the same God (Father) activates each gift in each person.
The Ante-Nicene Fathers:
There is a lot we can say about the influence of the early Christian Fathers and their conception of the Triune God but it is important to note as Patristic scholar Christopher A. Hall writes:
“The Fathers of the Church formulated the doctrine of the Trinity because they believed a faithful and careful reading of the Bible drove them to do so. Patristic theology, then, is first and foremost based on careful exegesis.” [Sola Scriptura & Tota Scriptura]. 
When we look at the Fathers, we can see a distinct interaction with the Biblical scriptures with an emphasis on its meaning. It is also external pressures that demanded an explanation for the Doctrine of the Trinity which they proposed. J.D. Douglas & F.F. Bruce write:
“The necessity to formulate the doctrine was thrust upon the Church by forces from without, and it was, in particular, its faith in the deity of Christ, and the necessity to defend it, that first compelled the Church to face the duty of formulating a full doctrine of the Trinity for its rule of faith.”
The Church Fathers on the nature of the Trinity (Father, Son, and Holy Spirit).
1) Father, Son, Spirit: Distinct persons yet one.
Ignatius of Antioch (35-108 AD).
Ignatius, second bishop of Antioch, who was martyred in Rome around 110 AD, wrote a series of letters to churches in Asia Minor on his way to be executed in Rome. The conjunction of Father, Son, and Holy Spirit appears in his letter to the Magnesian church:
“Study, therefore, to be established in the doctrines of the Lord and the apostles, that so all things, whatsoever ye do, may prosper both in the flesh and spirit; in faith and love; in the Son, and in the Father, and in the Spirit;”
Polycarp of Smyrna (65- 155 AD)
He was martyred in Smyrna (where he was also Bishop) in the year 155. Irenaeus of Lyons says that he was a pupil of the Apostle John.
“For this cause, yea and for all things, I praise Thee, I bless Thee, I glorify Thee, through the eternal and heavenly High-priest, Jesus Christ, Thy beloved Son, through whom with Him and the Holy Spirit be glory both now [and ever] and for the ages to come. Amen.”
Athanasius of Alexandria (296-373 AD).
Athanasius mentions a discussion wrote down between Pope Dionysius and Dionysius of Alexandria in the early second century where they are discussing Sabellianism.
“For it must be that with the God of the Universe, the Divine Word is united, and the Holy Ghost must repose and habitate in God; thus in one as in a summit, I mean the God of the Universe, must the Divine Trinity be gathered up and brought together….Neither, then, may we divide into three godheads the wonderful and divine Unity…Rather, we must believe in God, the Father Almighty; and in Christ Jesus, his Son; and in the Holy Spirit; and that the Word is united to the God of the universe. ‘For,’ he says, ‘The Father and I are one,’ and ‘I am in the Father, and the Father in me’. For thus both the Divine Trinity and the holy preaching of the Monarchy will be preserved.”
Gregory Bishop of Neocaesarea (213-270 AD).
Gregory wrote down a standard declaration of faith that was welcomed all over the Churches as a standard pre-Nicaean affirmation of what the Church held dear.
“There is one God, the Father of the living Word, who is His subsistent Wisdom and Power and Eternal Image: perfect Begetter of the perfect Begotten, Father of the only-begotten Son. There is one Lord, Only of the Only, God of God, Image and Likeness of Deity, Efficient Word, Wisdom comprehensive of the constitution of all things, and Power formative of the whole creation, true Son of true Father, Invisible of Invisible, and Incorruptible of Incorruptible, and Immortal of Immortal and Eternal of Eternal. And there is One Holy Spirit, having His subsistence from God, and being made manifest by the Son, to wit to men: Image of the Son, Perfect Image of the Perfect; Life, the Cause of the living; Holy Fount; Sanctity, the Supplier, or Leader, of Sanctification; in whom is manifested God the Father, who is above all and in all, and God the Son, who is through all. There is a perfect Trinity, in glory and eternity and sovereignty, neither divided nor estranged wherefore there is nothing either created or in servitude in the Trinity; nor anything superinduced, as if at some former period it was non-existent, and at some later period it was introduced. And thus neither was the Son ever wanting to the Father, nor the Spirit to the Son; but without variation and without change, the same Trinity abideth ever”
2) The Son as a distinct divine person.
Polycarp (69–155 AD)
In his Letter to the Philippians, he says,
“Now may the God and Father of our Lord Jesus Christ, and the eternal high priest himself, the Son of God Jesus Christ, build you up in faith and truth…and to us with you, and to all those under heaven who will yet believe in our Lord and God Jesus Christ and in his Father who raised him from the dead.”
Ignatius of Antioch (AD 50–117AD)
Ignatius was the bishop at the church in Antioch and a disciple of John the Apostle. He writes,
“There is only one physician, who is both flesh and spirit, born and unborn, God in man, true life in death, both from Mary and from God, first subject to suffering and then beyond it, Jesus Christ our Lord.”
“For our God, Jesus the Christ was conceived by Mary according to God’s plan, both from the seed of David and of the Holy Spirit.”
Justin Martyr (100–165 AD)
Justin was a Christian apologist of the second century.
“And that Christ being Lord, and God the Son of God, and appearing formerly in power as Man, and Angel, and in the glory of fire as at the bush, so also was manifested at the judgment executed on Sodom, has been demonstrated fully by what has been said.”
“Permit me first to recount the prophecies, which I wish to do in order to prove that Christ is called both God and Lord of hosts.”
“Therefore these words testify explicitly that He [Jesus] is witnessed to by Him [the Father] who established these things, as deserving to be worshipped, as God and as Christ.”
“Hence are we called atheists. And we confess that we are atheists, so far as gods of this sort are concerned, but not with respect to the most true God, the Father of righteousness and temperance and the other virtues, who is free from all impurity. But both Him, and the Son (who came forth from Him and taught us these things, and the host of the other good angels who follow and are made like to Him), and the prophetic Spirit, we worship and adore, knowing them in reason and truth, and declaring without grudging to everyone who wishes to learn, as we have been taught.”
Irenaeus of Lyons (AD 130–202 AD)
Irenaeus was bishop of Lyons, France. He studied under Bishop Polycarp, who in turn had been a disciple of John the Apostle.
“For I have shown from the Scriptures, that no one of the sons of Adam is as to everything, and absolutely, called God, or named Lord. But that He is Himself in His own right, beyond all men who ever lived, God, and Lord, and King Eternal, and the Incarnate Word, proclaimed by all the prophets, the apostles, and by the Spirit Himself, may be seen by all who have attained to even a small portion of the truth.”
“Christ Jesus [is] our Lord, and God, and Savior, and King, according to the will of the invisible Father.”
Clement of Alexandria (150–215 AD)
Clement was another early church father. He wrote around AD 200. He writes,
“This Word, then, the Christ, the cause of both our being at first (for He was in God) and of our well-being, this very Word has now appeared as man, He alone being both, God and man—the Author of all blessings to us; by whom we, being taught to live well, are sent on our way to life eternal…. The Word, who in the beginning bestowed on us life as Creator when He formed us, taught us to live well when He appeared as our Teacher that as God He might afterwards conduct us to the life which never ends.”
“the Savior, the clement, the Divine Word, He that is truly most manifest Deity, He that is made equal to the Lord of the universe; because He was His Son, and the Word was in God”
Tertullian (AD 150–225 AD)
Tertullian was an early Christian apologist. He said,
“Bear always in mind that this is the rule of faith which I profess; by it I testify that the Father, and the Son, and the Spirit are inseparable from each other, and so will you know in what sense this is said. Now, observe, my assertion is that the Father is one, and the Son one, and the Spirit one, and that they are distinct from each other. This statement is taken in a wrong sense by every uneducated as well as every perversely disposed person, as if it predicated a diversity, in such a sense as to imply a separation among the Father, and the Son, and the Spirit. I am, moreover, obliged to say this, when they contend for the identity of the Father and Son and Spirit, that it is not by way of diversity that the Son differs from the Father, but by distribution: it is not by division that He is different, but by distinction; because the Father is not the same as the Son, since they differ one from the other in the mode of their being. As if in this way also one were not All, in that All are of One, by unity (that is) of substance; while the mystery of the dispensation is still guarded, which distributes the Unity into a Trinity, placing in their order the three Persons—the Father, the Son, and the Holy Ghost: three, however, not in condition, but in degree; not in substance, but in form; not in power, but in aspect; yet of one substance, and of one condition, and of one power, inasmuch as He is one God, from whom these degrees and forms and aspects are reckoned, under the name of the Father, and of the Son, and of the Holy Ghost.”
3) The Holy Spirit as a distinct divine person.
Ignatius of Antioch (30–107 AD)
But the Holy Spirit does not speak His own things, but those of Christ, and that not from himself, but from the Lord; even as the Lord also announced to us the things that He received from the Father. For, says He,
“the word which ye hear is not Mine, but the Father’s, who sent Me.” And says He of the Holy Spirit, “He shall not speak of Himself, but whatsoever things He shall hear from Me.” And He says of Himself to the Father, “I have,” says He, “glorified Thee upon the earth; I have finished the work which, Thou gavest Me; I have manifested Thyname to men.” And of the Holy Ghost, “He shall glorify Me, for He receives of Mine.” 
“so also did the prophets and the apostles receive from God, through Jesus Christ, one and the same Holy Spirit, who is good, and sovereign, and true, and the Author of [saving] knowledge. For there is one God of the Old and New Testament, “one Mediator between God and men,” for the creation of both intelligent and sensitive beings, and in order to exercise a beneficial and suitable providence [over them]. There is also one Comforter, who displayed His power in Moses, and the prophets, and apostles.
Clement of Alexandria (153–217 AD)
“Thus also we who are baptized, having wiped off the sins which obscure the light of the Divine Spirit, have the eye of the spirit free, unimpeded, and full of light, by which alone we contemplate the Divine, the Holy Spirit flowing down to us from above.”
Tertullian of Carthage (160-220 AD)
“If the Holy Ghost took upon Himself so great a concern for our instruction, that we might know from what everything was produced, would He not in like manner have kept us well informed about both the heaven and the earth, by indicating to us what it was that He made them of, if their original consisted of any material substance, so that the more He seemed to have made them of nothing, the less in fact was there as yet made, from which He could appear to have made them?”
“the Father is God, and the Son is God, and the Holy Ghost is God, and each is God; but because in earlier times Two were actually spoken of as God, and two as Lord, that when Christ should come He might be both acknowledged as God and designated as Lord, being the Son of Him who is both God and Lord. Besides, if, from that perfect knowledge which assures us that the title of God and Lord is suitable both to the Father, and to the Son, and to the Holy Ghost,
“Then there is the Paraclete or Comforter, also, which He promises to pray for to the Father, and to send from heaven after He had ascended to the Father. He is called “another Comforter,” indeed; but in what way He is another we have already shown, “He shall receive of mine,” says Christ, just as Christ Himself received of the Father’s. Thus the connection of the Father in the Son, and of the Son in the Paraclete, produces three coherent Persons, who are yet distinct One from Another.”
Novatian, Presbyter of Rome (210–280 AD)
“Moreover, the order of reason, and the authority of the faith in the disposition of the words and in the Scriptures of the Lord, admonish us after these things to believe also on the Holy Spirit, once promised to the Church, and in the appointed occasions of times given. For He was promised by Joel the prophet, but given by Christ. “In the last days,” says the prophet, “I will pour out of my Spirit upon my servants and my handmaids.” And the Lord said, “Receive ye the Holy Ghost: whose sins ye remit, they shall be remitted; and whose ye retain, they shall be retained.” But this Holy Spirit the Lord Christ calls at one time “the Paraclete,” at another pronounces to be the “Spirit of truth.” And He is not new in the Gospel, nor yet even newly given; for it was He Himself who accused the people in the prophets, and in the apostles gave them the appeal to the Gentiles.”
Dionysius of Alexandria (200–265 AD).
“For it is essential that the Divine Word should be united to the God of all, and that the Holy Spirit should abide and dwell in God; and thus that the Divine Trinity should be reduced and gathered into one, as if into a certain head—that is, into the omnipotent God of all.”
Alexander, Bishop of Alexandria. (273–326 AD).
“And besides the pious opinion concerning the Father and the Son, we confess to one Holy Spirit, as the divine Scriptures teach us; who hath inaugurated both the holy men of the Old Testament and the divine teachers of that which is called the New.”
We started with the Pre-Apostolic age and found that the very idea of a plurality and unity was not a foreign concept minted out by even the earliest Jewish minds and Scriptures. The Old Testament articulates nothing of a definite oneness and the central point of the Shema is a call to obey, not necessarily to define the ‘definite’ oneness of God. The Old Testament reveals that Yahweh, the Angel of Yahweh, and the Spirit of Yahweh are clearly distinct yet; it does not deny the unity of the One God.
Secondly, we found that in the Apostolic age both the Gospel authors and Paul clearly articulate an understanding that God is revealed as Father, Son, and Holy Spirit, not confused with One another, yet, still all the One God.
Lastly, this reality is also evident in the earliest Church Fathers, and we find them absolutely affirming the reality that God revealed Himself as ‘Tri-personal’, and distinguished as unique in His own self-revelation. As Paul wrote to the Ephesian Church: “For through him we both have access in one Spirit to the Father” (Eph. 2:18).
 “Besides all this and before all, keep I pray you the good deposit, by which I live and work, and which I desire to have as the companion of my departure; with which I endure all that is so distressful, and despise all delights; the confession of the Father and the Son and the Holy Ghost. This I commit unto you today; with this I will baptize you and make you grow. This I give you to share, and to defend all your life, the One Godhead and Power, found in the Three in Unity, and comprising the Three separately, not unequal, in substances or natures, neither increased nor diminished by superiorities or inferiorities; in every respect equal, in every respect the same; just as the beauty and the greatness of the heavens is one; the infinite conjunction of Three Infinite Ones, Each God when considered in Himself; as the Father so the Son, as the Son so the Holy Ghost; the Three One God when contemplated together; Each God because Consubstantial; One God because of the Monarchia. No sooner do I conceive of the One than I am illumined by the Splendour of the Three; no sooner do I distinguish Them than I am carried back to the One. When I think of any One of the Three I think of Him as the Whole, and my eyes are filled, and the greater part of what I am thinking of escapes me. I cannot grasp the greatness of That One so as to attribute a greater greatness to the Rest. When I contemplate the Three together, I see but one torch, and cannot divide or measure out the Undivided Light”.
~ Gregory of Nazianzus, Orations 40.41. Preached at Constantinople Jan. 6, 381 A.D.
Source. Translated by Charles Gordon Browne and James Edward Swallow. From Nicene and Post-Nicene Fathers, Second Series, Vol. 7. Edited by Philip Schaff and Henry Wace.
 OT: Deut. 4:35; 4:39; 32:39; 2 Sam. 22:32; Isa. 37:20: 43:10; 44:6-8; 45:5; 45:14; 45:21-22; 46:9.
NT: John 5:44; Rom. 3:30; 16:27; 1 Cor. 8:4-6; Gal. 3:20; Eph. 4:6; 1 Tim. 1:17; 1 Tim. 2:5; James 2:19; Jude 25.
 Kenneth Gragg: “Belief in the Trinity does not make God less one but rather more one”… “for in Christ, God demonstrates that he alone is God.”
Source: The Call of the Minaret. Pg.264, 283.
 Matt. 28:19; 2 Cor. 13:3-4; also Luke 1:35; 3:21-22 par.; Luke 4:1-12; John 4:10-25; 7:37-39; 7:14-16; 20:21-22; Acts 1:4-8; 2:33, 38-39; 5:3-4, 5:9, 5:30-32; 7:55-56; 10:36-38, 10:44-48; 11:15-18; 15:8-11; 20:38; 28:25-31; Rom. 1:1-4; 5:5-10; 8:2-4, 8:9-11, 8:14-17; 1 Cor. 6:11; 12:4-6, 12:11-12, 12:18; 2 Cor. 1:19-22; 3:6-8, 3:14-18; Gal. 3:8-14; 4:4-7; Eph. 1:3-17; 2:18, 2:21-22; 3:14-19; 4:4-6, 4:29-32; 5:18-20; Phil. 3:3; 1 Thess. 1:3-6; 2 Thess. 2:13-14; Tit. 3:4-6; Heb. 2:3-4; 9:14; 10:28-31; 1 Pet. 1:2; 1 John 3:21-24; 4:13-14; Jude 20-21; Rev. 2:18, 2:27-29.
 “The true God exists not only in oneness, but also in relationship. This relationship is between the three persons within the oneness of God, so that there are not three gods. But these three persons are not modes,but are rather distinct persons from one another. These persons share in the same essence without subordinationism, and mutually indwell one another without ceasing. So the true God combines all these aspects together… the New Testament reveals the Trinity in simplicity, without explaining it and without apology for proclaiming it. Believers do not deal with a distant God who is uncaring about his creation, but they are related to God as a Father who loves them, in the name of the Son who redeemed them, and in the intercession of the Holy Spirit who lives within them.”
Source: “God with us and without us: Volume one. Oneness in Trinity versus Absolute oneness.” Pg 85 & 92
 John 1:1 , 18; John 20:28, John 17:3; 1 Cor. 8:6; Acts 5:3-4; 2 Cor. 3:17-18
 “One is the light from the sun in the radiance; and so we know of but one origin; and the All-framing Word we profess to have no other manner of godhead, than that of the Only God, because He is born from Him. Rather than will the Ario-maniacs with reason incur the charge of polytheism or else of atheism, because they idly talk of the Son as external and a creature, and again the Spirit as from nothing.
For either they will say that the Word is not God; or saying that He is [a lesser] God, because it is so written, but not proper to the Father’s Essence, they will introduce many because of their difference of kind (unless forsooth they shall dare to say that by participation only, He, as all things else, is called God; though, if this be their sentiment, their irreligion is the same, since they consider the Word as one among all things). But let this never even come into our mind.
For there is but one form of Godhead, which is also in the Word; and one God, the Father, existing by Himself according as He is above all, and appearing in the Son according as He pervades all things, and in the Spirit according as in Him He acts in all things through the Word. For thus we confess God to be one through the Triad, and we say that it is much more religious than the godhead of the heretics with its many kinds, and many parts, to entertain a belief of the One Godhead in a Triad… either He is not True God because He is Himself one of the creatures, or if they name Him God from regard for the Scriptures, they must of necessity say that there are two Gods, one Creator, the other creature, and must serve two Lords, one Unoriginate, and the other originate and a creature; and must have two faiths, one in the True God, and the other in one who is made and fashioned by themselves and called God.
And it follows of necessity in so great blindness, that, when they worship the Unoriginate, they renounce the originate, and when they come to the creature, they turn from the Creator. For they cannot see the One in the other, because their natures and operations are foreign and distinct”.
~ Athanasius of Alexandria (296-373 A.D.). Source: Select Works and Letters. Discourse 3. 15-16.
 The Forgotten Trinity.
 Herman Bavinck (1854-1921). Professor at Vrije Universiteit, Amsterdam writes; “Among creatures distinctions necessarily indicate manyness, division, separateness. Creatures exist side by side; they follow one another in space and time. But eternity, omnipresence, omnipotence, goodness, etc. do not admit of partition and distribution. God is absolute unity and simplicity, without any composition or division: and that unity is not contractual or ethical as among men, but absolute: is not accidental but essential to God’s being. Now the glory of the doctrine of the Trinity consists in this that God’s absolute unity does not exclude but demands diversity. The being of God is not an abstract unity; it is not an abstract idea but a fullness of essence, an infinite abundance of life whose diversity unfolds the highest unity. The self-distinctions within the Divine Being, which in Scripture are designated by terms “Father”, “Son”, and, “Holy Spirit” are called ‘persons’ in Theology.”
 “Echad” is a compound unity (Gen.2:24; 11:6) and “Eloheinu” – ‘Inu’ = The Plural possessive pronoun suffix which also announce a plural unity
Numbers 20:15 [ ABTH’INU] “Our Father.”
Isaiah 53:5 [AUNTH’INU] “Our iniquities.”
1 Samuel 12:19 [CHTATH’ INU] “Our Sins.”
 Unfortunately, the view of Maimonides is reactionary and also goes beyond what is stated in the Scriptures. In fact, there is not a single verse anywhere in the Bible that clearly or directly states that God is an absolute unity Answering Jewish Objections to Jesus: Theological Objections [Baker Books, Grand Rapids MI, 2000], Volume Two, pg. 4
 The New Testament and the people of God: Pg.258-259.
 “The Meaning of Jesus” Pg.159-160.
 Genesis. The JPS Torah Commentary, Pg.383.
 From the Zohar, which is an early 2nd century work ascribed to Shimon bar Yochai (“Rashbi”), a rabbi under the Roman persecution saying to his son Eliezer:
“Come and see the mystery of the word YHVH: there are three steps, each existing by itself: nevertheless they are One, and so united that one cannot be separated from the other. The Ancient Holy One is revealed with three heads, which are united into one, and that head is three exalted. The Ancient One is described as being three: because the other lights emanating from him are included in the three. But how can three names be one? Are they really one because we call them one? How three can be one can only be known through the revelation of the Holy Spirit.”
 B. B. Warfield writes: The Old Testament may be likened to a chamber richly furnished but dimly lighted; the introduction of light brings into it nothing, which was not in it before; but it brings out into clearer view much of what is in it but was only dimly or even not at all perceived before. The mystery of the Trinity is not revealed in the Old Testament; but the mystery of the Trinity underlies the Old Testament revelation, and here and there almost comes into view. Thus the Old Testament revelation of God is not corrected by the fuller revelation that follows it, but only perfected, extended and enlarged.”
 Gen.16:22, 31; Exo.3; 14; Num.22; Judg.2,6,13; Zech.3;12; Ps.45:7
 1 Sam.10:10, 19:20; Exo.31:3; Num.24:2; Judg.3:10; Job 3:4; Isaiah 63:11-12; Ps.51; Ezek.11:5; 2 Sam.23:2-3.
 Rabbi Eliezer Hakkalir, The Book of Creation, p. 89
 1912, Vol. 15, p 47-49.
 “Indeed, the mystery of Christ runs the risk of being disbelieved precisely because it is so incredibly wonderful. For God was in humanity. He who was above all creation was in our human condition; the invisible one was made visible in the flesh; He who is from the heavens and from high was in the likeness of earthly things; the immaterial One could be touched; He who is free in His own nature came in the form of a slave; He who blessed all creation became accursed; He who is all righteousness was numbered among transgressors; life itself came in the appearance of death. All this followed because the body which tasted death belonged to no other but to Him who is the Son by nature.”
~ Cyril of Alexandria. (378 AD – 444 AD). Source: “On the Unity of Christ.”
 John 16:7; 13-15 “I am telling you the truth. It is for your benefit that I go away, because if I don’t go away the Counselor will not come to you. If I go, I will send Him to you. When the Spirit of truth comes, He will guide you into all the truth. For He will not speak on His own, but He will speak whatever He hears. He will also declare to you what is to come. He will glorify Me, because He will take from what is Mine and declare it to you. Everything the Father has is mine. This is why I told you that He takes from what is Mine and will declare it to you.”
 “it will be maintained that this pattern of Christ-relation language in Paul is only that which a Jew used to express the relation between Israel/ the individual Jew and YHWH. No other figure of any kind, apart from YHWH, was related to in the same way, with the same pattern of language, not even the various exalted human and angelic intermediary figures in the literature of Second Temple Judaism that occasionally receive worship and are described in very exalted terms”… “to speak of a Pauline ‘strict’ monotheism, of God’s transcendent uniqueness, is not out of place. Further, this unique divine transcendence is expressed relationally, through a pattern of God-relation data unique to God alone”.
~Prof. Chris Tilling. Source: Paul’s Divine Christology Pg.73-
 J. N. D. Kelly writes: “The ideas implicit in [the] early catechedical and liturgical formulae, as in the New Testament writers’ use of the same dyadic and triadic patterns, represent a pre-reflective, pre-theological phase of Christian belief. It was out of the raw material thus provided by the preaching, worshiping Church that theologians had to construct their more sophisticated accounts of the Christian doctrine of the Godhead. Early Christian Doctrines, pg. 90
 Learning theology with the Church Fathers, Pg. 55. I.V.P. Press.
 Gerald Bray writes: “Orthodoxy was felt before it was articulated….
Gerald Bray. Creeds, Councils, and Christ. Pg.73 + Pg.91.
 New Bible Dictionary, Trinity, p 1298
 NOVATIAN OF ROME (CA.256) presbyter of Rome wrote a whole treatise entitled ‘’On the Trinity”
“For Scripture as much announces Christ as also God, as it announces God himself as man. It has as much described Jesus Christ to be man, as moreover it has also described Christ the Lord to be God. Because it does not set forth him to be the Son of God only, but also the son of man; nor does it only say, the son of man, but it has also been accustomed to speak of him as the Son of God. So that being of both, he is both, lest if he should be one only, he could not be the other. For as nature itself has prescribed that he must be believed to be a man who is of man, so the same nature prescribes also that he must be believed to be God who is of God…. Let them, therefore, who read that Jesus Christ the son of man is man, read also that this same Jesus is called also God and the Son of God.”
 Epistle to the Magnesians, Chapter 13.
 Martyrdom of Polycarp 14:3
 De decretis Nic. syn.26
 Philippians, 12:2.
 Letter to the Ephesians, 7.2.
 Letter to the Ephesians, 18.2.
 Dialogue with Trypho, 128. Translation from Alexander Roberts and James Donaldson, Ante-Nicene Fathers, I:264.
 Dialogue with Trypho, 36. ANF, I:212.
 Dialogue with Trypho, 63. ANF, I:229.
 Chapter 6 of his First Apology
 Against Heresies, 3.19.2.
 Against Heresies, 1.10.1.
 Exhortation to the Heathen, 1.
 Exhortation to the Heathen, 10.
 Against Praxeas, chapter 2.
 The Epistle of Ignatius to the Ephesians Chapter IX
 “They introduce God as a Being unknown; they suppose Christ to be unbegotten; and as to the Spirit, they do not admit that He exists. Some of them say that the Son is a mere man, and that the Father, Son, and Holy Spirit are but the same person, and that the creation is the work of God, not by Christ, but by some other strange power.” The Epistle of Ignatius to the Trallians Chapter VI
 The Epistle of Ignatius to the Philadelphians Chapter V.—Pray for me.
 The Instructor – Chapter VI
 Against Hermogenes. Chapter XXII.—This Conclusion Confirmed by the Usage of Holy Scripture in Its History of the Creation. Hermogenes in Danger of the Woe Pronounced Against Adding to Scripture.
 Against Praxeas Chapter XIII
 Against Praxeas Chapter XXV
 A Treatise of Novatian Concerning the Trinity. Chapter XXIX.
 Against the Sabellians 1.
 Epistles on the Arian Heresy And the Deposition of Arius I.12