In the Beginning Was the Word, Jesus Christ — Eternal God Became Flesh

‘This is the most amazing event in all of history’

In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through him, and without him was not any thing made that was made. In him was life, and the life was the light of men. The light shines in the darkness, and the darkness has not overcome it. (John 1:1-5, English Standard Version) …

And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. (John 1:14, ESV)

ESV Study Bible commentary notes on John 1:3 (emphasis theirs):

1:3  All things includes the whole universe, indicating that (except for God) everything that exists was created and that (except for God) nothing has existed eternally. Made though him follows the consistent pattern of Scripture in saying that God the Father carried out his creative works through the activity of the Son (cf. 1 Cor 8:6; Col. 1:16; Heb. 1:2). This verse disproves any suggestion that the Word (or the Son, John 1:14) was created, for the Father would have had to do this by himself, and John says that nothing was created that way, for without him was not any thing made that was made.

Partial ESV Study Bible commentary notes on John 1:14 (emphasis theirs):

1:14  The Word continues the opening words of the prologue in v. 1. Became flesh does not mean the Word ceased being God; rather, the Word, who was God, also took on humanity (cf. Phil. 2:6-7). This is the most amazing event in all of history: the eternal, omnipotent, omnipresent, infinitely holy Son of God took on a human nature and lived among humanity as one who was both God and man at the same time, in one person.