Summary: The sacred mystery of Christmas is the Incarnation, that God became flesh and made His dwelling among us. The world opposes this mystery as irrational and offensive, because it points to our fallen nature and need for a Savior.
The Mystery of Christmas, what makes it special, is the Incarnation. A mystery is not part of our human, rational understanding. It is sublime, and part of divine revelation. Non-Christians can witness the events of Christmas—the baby in the manger, etc.—but without God’s revelation, their understanding is limited to the empirical and rational experience of the season. Only with the touch of God is the mystery of the Incarnation opened. It transcends what we can know.
The child Jesus is a sign. Isaiah prophesied, “Therefore, the LORD himself will give you a sign: The virgin will be with child and will give birth to a son and will call him Immanuel” (Is. 8:14), that is, God with us. Isaiah’s prophesy what that a child would signify that the word of the Lord that Israel would not be destroyed by its enemies was true. Jesus came as a sign to show all men that despite the appearances of death and destruction, God is victorious, and He triumphs. Not only is the Christ Child a sign, He is the thing signified. He is the victory over death; He is triumph. And so, John opens his Gospel.
John 1:1–2. God is eternal, from before time. He always was, always is, and always shall be. YHWH. “‘I am the Alpha and the Omega,’ says the Lord God, ‘who is, and who was, and who is to come, the Almighty’” (Rev. 1:8). The Word was with God in the beginning, before creation began; there was never a time that the Word was not.
John 1:3. God created everything. This sounds obvious, doesn’t it? But our advanced, modern culture has, through the miracles of science, largely abandoned this belief. Yet science shows that this universe in it earliest moments was a point—that it had an origin and start. Some scientists postulate that there was a former state from which our universe’s earliest moments began, but this chain of causality only points to a single, primordial mover, the first cause, the originator.
John 1:4. God is life, and He is the light of men. Jesus said, “I am the Living One; I was dead, and behold I am alive for ever and ever. I hold the keys of death and Hades” (Rev. 1:18. Jesus, rising from the grave, proved that His power is that of life, life that exceeds the seemingly unbreakable grip of death. Jesus said, “I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life” (Jn. 8:12).
John 1:5. Men did not understand the light, hence the life, of God. Another translation of “understand” is “overcome,” and John’s Gospel is sufficiently rich to assume that he meant both nuances. The darkness does not “understand” the light, because it cannot perceive the meaning of it. Light wipes darkness away, so there can be no knowing. Also, darkness cannot overcome light. Evil (darkness) is parasitic; it corrupts good, but it cannot exist without a good to corrupt. But good (light) has existence of itself. For example, is moldy bread good or bad? It’s bad. But the mold has no existence apart from the bread. The true light is the true bread come down from heaven, that never molds or spoils or goes stale, but is always fresh.