The pre-incarnated Christ existed long before His birth in Bethlehem.

John 1:1-3 In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made through him; and without him was not anything made that hath been made.

In the Old Testament there are several manifestations of His existence which are known as THEOPHANIES literally “The appearance of God”.

It is a visible manifestation of God to humankind.

One of these appearances is recorded in:

Daniel 3:25 Did not we cast three men bound into the midst of the fire? They answered and said unto the king, True, O king. He answered and said, Lo, I see four men loose, walking in the midst of the fire, and they have no hurt; and the form of the fourth is like the Son of God.

These are very different from His appearance as a babe in Bethlehem which is known as His INCARNATION literally “God in the flesh”.

John 1:14 And the Word was made flesh, and dwelt among us.

The Incarnation of the Son of God is the terminology used to describe what happened when the second person of the Trinity, the eternal Son of God, “became flesh” as he was miraculously conceived in the womb of the Virgin Mary. In the incarnation, the divine nature of the Son was perfectly united with human nature in one divine Person. This person, Jesus Christ, was both “truly God and truly man.”

Charles Wesley penned it so well in his Christmas carol

“Hark the Herald Angels Sing”

Veiled in flesh the Godhead see
Hail the incarnate Deity
Pleased as man with man to dwell
Jesus, our Emmanuel
Hark! The herald angels sing
Glory to the newborn King!
Philippians 3:6 Who, being in the form of God, thought it not robbery to be equal with God: But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men
Mild He lays His glory by
Born that man no more may die
Born to raise the sons of earth
Born to give them second birth
Hark! The herald angels sing
Glory to the newborn King!