God came as man in the person of Jesus Christ

The hypostatic union- the Son as the visible representation of the invisible Father, that he took on human flesh- two natures in one person, 100% humanity and 100% deity. Each are their own nature that did not intermingle but made up the person of Jesus.

Col 1:15 “He is the image of the invisible God, the firstborn over all creation.”

The word firstborn does not have anything to do with born. It means first in rank, an heir, to have preeminence in position, not origin. As in Rev.1:5, Heb.1:5-6 both clarify the meaning of firstborn by its context. Christ was not the first raised from the dead to eternal life in the body. Which gives him headship over the human race.

The Father is over the Son positionally, just as the husband is the same nature as his wife but over his wife in position

The writer is conveying the exact expression (the image) of the invisible God was made known to mankind through a man. He was precisely like his Father in nature who remained invisible in every respect.

The answer to all this is found in His state of humiliation- taking up the human condition from his conception, the form of man on earth. Growing to the time of being 30 years of age and being revealed to Israel.

Phil.2:5-8 “Who being in the form of (nature) God (Gal. 4:8: there is only one God by nature) did not consider it robbery to be equal with God. v.7: But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men (in nature).”

In becoming a man something changed, since he was not in a servant role to the Father before He came to earth and became man. This was a change of position, not a change in nature. He, as God, could not empty himself of His essential nature, since unchangeableness is part of his nature (Mal.3:6). All His attributes are eternal so he could not eliminate any but he could put them aside in using them as He entered time and space to reach mankind. That is how powerful God is.

“Their was a voluntary emptying to give up his independent use of his divine attributes while living on earth in a subordinate role to the Father. This did not change his nature as being the Son of God. That Christ gave up the “Independent exercise of the divine attributes” (Strongs Systematic Theology p.382).

in other words he was still fully deity, divine, but did not use his ability as God unless the Father instructed him and  had the Holy Spirit involved.

The Son is just as real and present before the creation of the world as the Father is. He is, as the Father says, the creator. Col 1:16 “For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him.” In other words, the Father, and the Holy Spirit were also involved  in creation.

This means everything that exists he (the Son) created them. As stated in Jn.1:2: “He was in the beginning (already existing) with God.” v.3: “All things were (past tense) made through Him, (a person) Without Him nothing (which means nothing) was made that was made.”  

Which means the Son is the author of all and must be God according to the Bible.

Jesus says in John 17 "And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was.” If the worlds was the first thing God created (Gen.1:1) and the son had the same glory as the Father then he is God. He took upon himself another nature when he was born through the virgin, his mother Mary.

This is why John writes (1:14) “And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth.”

And he follows with the mystery of the incarnation “No one has seen God at any time. The only begotten Son, who is in the bosom of the Father, He has declared Him” (John 1:18) The son has made him known to us.