The incarnation is as mysterious to believers as any doctrine of the faith. I have often wondered why we do not admit this more often. My guess is that we are too comfortable with this truth because of the trappings of Christmas and the culture in which we live.
People often talk about the mystery of good and evil, or divine sovereignty and human freedom. Admittedly these are difficult truths and even divide Christians among themselves. But no truth is more mysterious, so far as I am concerned, than this: The second person of the Godhead, the eternal logos, took upon himself human flesh (a human nature in every sense of the word) and thus God became man. Now I know that without the death and resurrection of Jesus there is no salvation but there could be no death and resurrection unless there were first an incarnation. Further, the Scripture clearly treats the incarnation as a much more central to our redemption than many of us do.
I looked up a few quotations in John Calvin today to see what he said about the advent of Christ and the incarnation. Here are a few choice Calvin comments:
"It is impossible to express in human language adequate to the subject the glory with which Christ beautified his church by his advent."
"As often as God appeared under the form of man, an obscure glimpse was afforded of the mystery which was at length manifested in the person of Christ."
"We assert such a connection and union of the divinity and the humanity, that each nature retrains its properties entire, and yet both together constitute the one Christ."
Jesus of Nazareth is the divine logos, thus clearly God. He was with God from before all time says the Fourth Gospel thus the one born Jesus of Nazareth did not have his beginning in his birth at Bethlehem. He is the eternal son of God, without beginning. There never was a time when he was not and thus when the Son of God did not exist as the Son of God. But he became flesh, that is the man Christ Jesus did not exist before the incarnation. Thus he is both God and man, doing what is perfectly appropriate for both natures in one person. The two natures are in union without confusion.
The Orthodox Church has emphasized that by the incarnation the human nature of mankind is "energized" by the incarnation of Christ. By this they teach that the incarnation redeems humanity through the divine energy of the Son of God. He "deifies" human nature in a properly and carefully understood sense.
Perhaps a deeper and richer understanding of the wonder of this truth would make this day more meaningful to multitudes. I would have to believe this is true based on what I've witnessed over the course of my own life on this earth.