Christmas was not, as it turns out, miraculously handed down as a fully formed holiday, complete with wrapped gifts and blinking lights. Rather, it is a rich tapestry woven from countless inexplicable and pointless customs.
Why December 25th?
The Bible doesn't give a lot of clues as to what time of the year the birth of Jesus happened (i.e., "... they met many travelers along the way, for it was just three days before the final game of the NFL Season...") So, why December 25th? No one knows for sure.
One likely explanation is that early church leaders needed a holiday to distract Christians from the many pagan revelries occurring in late December. One of the revelries was The Saturnalia, a week-long festival celebrating the Romans' favorite agricultural god, Saturn. From December 17 until December 23, tomfoolery and pagan hijinks ensued, and by hijinks we mean gluttonous feasting, drunkenness, gambling and public nudity.
The Romans would also switch roles between masters and slaves for the occasion, so not only did the slaves get to pathetically lower their own sense of self-worth by participating in the charade of freedom, they also got to wear a Pileus (roughly translated, "Freedom Hat").
Google Image Search result for "Freedom Hat"
Master: "Happy Saturnalia! Here's your freedom hat! We're equals!"
Slave: "Thank you, master!" (puts on hat and primps in the mirror)
Master: "Saturnalia is over! Give me back my hat! How dare you put a hat on your slave head! YOU SHALL TASTE THE WHIP TONIGHT, BOY.
One other pagan celebration that might have given Christmas its date was Natalis Solis Invincti, which roughly translates to "Birthday of the Invincible Sun God," giving it officially the most awesome holiday name ever.
By the 12th century, the Christian Church had incorporated a few of the less-sinful pagan traditions into the 12 days of Christmas. We only wish the public nudity could have been left in ... maybe on the 10th or 11th day. Along with the gambling. And the drinking. Then again, it appears everyday is Saturnalia in Vegas so maybe we'll just go there instead.