The Unitarian idea that the creation of the Church, rather than that of everything is in view in Colossians 1:16 is utterly inconceivable when the text is properly examined. Unitarians would like us to believe that In Colossians 1 the creation being spoken about is the arrangement and constitution of the Church, by Christ’s death or by some other means rather than a physical act of Creation by Christ. One of the chief propaganda arms of the Unitarian heresy, biblicalunitarian.com website states in defense of their interpretation:

“God delegated to Christ His authority to create. Ephesians 2:15 refers to Christ creating “one new man” (his Church) out of Jew and Gentile. In pouring out the gift of holy spirit to each believer (Acts 2:33 and 38), the Lord Jesus has created something new in each of them, that is, the “new man,” their new nature (2 Cor. 5:17; Gal. 6:15; Eph. 4:24).
 
The Church of the Body of Christ was a brand new entity, created by Christ out of Jew and Gentile. He had to also create the structure and positions that would allow it to function, both in the spiritual world (positions for the Angels that would minister to the Church—see Rev. 1:1, “his angel”) and in the physical world (positions and ministries here on earth—see Rom. 12:4-8; Eph. 4:7-11). The Bible describes these physical and spiritual realities by the phrase, “things in heaven and on earth, visible and invisible” (1:16).” (1)

This interpretation however cannot stand, either on exegetical nor linguistic grounds. Firstly, the word ἐκτίσθη is used of physical or actual creation. And physical or actual creation only. The allegorical or ethical interpretation of this word meaning some sort of “obtain(ing) its arrangement and constitution” (as per Schleiermacher) is not plausible.
This word could have this meaning, but most certainly not anywhere in the New Testament, and even more certainly not here.
Great NT scholar, Heinrich Meyer says in response to this interpretation that the word ἐκτίσθη is: “correlative with πάσης κτίσεως” and that after it “quite general and in no way to be restricted τὰ πάντα follows”. He continues to say that: “Throughout the N. T., in general κτίζω, κτίσις, κτίσμα, denote the original bringing forth, never merely the arrangement of that which exists; and even in such passages as Ephesians 2:10; Ephesians 2:15; Ephesians 4:24, the relation is conceived, only in a popular manner, as actual creation.” (2)

Meyer goes on to machinegun a list of verses from the Bible and Apocrypha where this is made perfectly clear and a few verses to compare with them also: ” Wis 1:14; Wis 10:1; Wis 11:18; Deuteronomy 4:32; comp. Genesis 6:7; Sir 24:9, comp. Sir 15:14; Jdt 13:18; comp. Genesis 1:1; 1 Corinthians 11:9; Ephesians 3:9; Romans 1:25; Revelation 10:6, comp. Revelation 14:7. ” (3)

This means that the meaning our Unitarian friends would like to bring forth is utterly inconceivable. Never is the word they would like to pervert used in a way they would like it, the surrounding words not only give us no indication that it should be used the way our heretical friends would like but rather completely contradict it since these words are used of God himself in creation. Oh, but we are not done with our Unitarian friends just yet. Let us see what Romans 11:36 has to say of Father’s role in creation:

“For from him and through him and to him are all things. To him be glory forever. Amen.”

In Greek: “ὅτι ἐξ αὐτοῦ καὶ δι’ αὐτοῦ καὶ εἰς αὐτὸν τὰ πάντα· αὐτῷ ἡ δόξα εἰς τοὺς αἰῶνας· ἀμήν.”

Quite interesting, now let’s compare parts of Colossians 1:16, side by side with the first part of Romans 11:36, remember, the passage in Colossians is about the Son, the one in Romans, about the Father.

GRK COL. 1:16 :”ὅτι ἐν αὐτῷ ἐκτίσθη τὰ πάντα…τὰ πάντα δι’ αὐτοῦ καὶ εἰς αὐτὸν ἔκτισται·”
GRK ROM. 11:36: “ὅτι ἐξ αὐτοῦ καὶ δι’ αὐτοῦ καὶ εἰς αὐτὸν τὰ πάντα·”

In both cases τὰ πάντα·(all things) are used of the act of creation.
In both cases, the creation is described as δι’ αὐτοῦ (through him)
In both cases, the creation is described as εἰς αὐτὸν (for him or unto him)
In both cases either ἐν αὐτῷ (by him) or ἐξ αὐτοῦ (from him) start the sentences, meaning the same thing. Oh, but we are still not done. 

There is a reason why Paul stated that Jesus is over all dominions and powers in heavens and on earth. At that time, Angel reverence and worship were quite prominent (as he describes just a bit later in Colossians 2:18). We have to also remember that Paul used the very same words in Ephesians 6:12 as he did in Colossians 1:16 to refer to spiritual powers (whether angelic or demonic):

“For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.”

Paul is clearly showing us the preeminence of Christ, his power and his position. That he is not a mere angel or a mere man whose actions somehow sprung off the Church but rather the Creator who is to be worshipped over all. I conclude with the words of blessed Irenaeus, scriptures disciple of Polycarp, who was himself, a disciple of the Apostle John:

“For I have shown, 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. Now, the Scriptures would not have testified these things of Him, if, like others, He had been a mere man.”

(Irenaeus Against Heresies, chapter xix.2)

References:

(1) www.biblicalunitarian.com/verses/colossians-1-15-20

(2)&(3) Meyer’s NT Commentary on Colossians 1:16