It really is an amazing thing to think about the mystery of the Incarnation - that mysterious moment when God became a man. Jesus Christ - God the Son - was born in a manger. He went from the throne of heaven to a feeding trough. He went from the presence of angels to a cave filled with animals. He who is larger than the universe became an embryo. He who sustains the world with a word chose to be dependent upon the nourishment of a young virgin.
Some people have a hard time believing in the Virgin Birth. If you believe the Bible, you need to believe in the Virgin Birth. The Bible teaches that God Almighty was supernaturally conceived in the womb of a virgin (see Matthew 1:23). This makes sense if you think about it. If God had chosen to, He could have sent Jesus to this earth as a fully grown, yet sinless human being. A shaft of light could have come out from heaven with Jesus descending to the ground as an adult man. But if Jesus came to us in that way, who could have related to Him as a person, as a part of the human race? God also could have had Jesus come into the world through two ordinary human beings - but still with a divine nature. But then most of us would have doubted His divinity. That's why the Incarnation makes sense.
The event of the Incarnation is the reason for the Christmas season. Christmas is the opportunity to worship God, to bow down and pay homage to Him for humbling Himself and appearing in human form (see Philippians 2:6-9). That stands as the true mystery of the Incarnation - and the reason we celebrate Christmas.
Taken from "Why We Celebrate Christmas" by Harvest Ministries (used by permission).