In The Fabulous First Centuries of Christianity, Vance Ferrell writes this:
Cumont, Olcott, and others clearly show that December 25 was the yearly date of the annual birth of Mithra, the Sun god—the leading heathen deity of the Empire. On this date, his followers celebrated the fact that the visible orb of the sun was again rising higher in the sky, following the winter solstice. (On December 21, the sun is actually at its lowest; but its rise is not visibly perceptible until four days later.) Emperor Aurelian made Mithra’s December 25 birthday an official holiday throughout the Empire about A.D. 273…This midwinter pagan holiday was eventually declared to be the solemn anniversary of the birth of Christ—and called "the mass of Christ." 
Depending on whom you ask, December 25 has a whole host of nefarious pagan characters laying claim to it. Mithra, Isis, Osiris, and Saturnalia are just a few of the names that get linked with this date. The general argument, illustrated by Ferrell’s quotation above, is that because December 25 is associated with so many pagan (or even worse, Roman Catholic) traditions and "deities," "real" Christians should not celebrate the day, or attribute any more significance to it than any other day of the year. While it is not my purpose in the least to defend December 25 as the actual date of Christ’s birth, I do think that ignoring the gift of the tradition of Christmas is just as much a problem as making too much of it by focusing on Santa Claus, reindeer, and Christmas trees.
As C.S. Lewis points out in his short article, "Exmas and Christmas," there are really two holidays on December 25. One is a strictly materialistic, pagan time of rushing around and spending money that we don’t have, while the other is about the Incarnation of Jesus Christ. Too many Christians try to marry these two holidays by attempting to sanctify the whole affair, finding the Gospel in everything from wreaths and candy canes to Christmas trees and gift-giving. While it is true that Jesus was God’s gift to us, I can’t quite find a parallel between God’s gift of His Son and my gift of a toy or a book to one of my children. There’s nothing particularly wrong with traditions, it’s when the traditions begin to control us that they become an issue. God commanded Israel to have many traditions that were meant to remind them of Him and His law, but in Mark 7, Jesus condemns the Pharisees and scribes for trusting in the traditions themselves, rather than the Object of the tradition. It is very easy to take the materialistic aspect of Christmas (what Lewis calls Exmas) too far, but rather than trying to Christianize our materialism, we should always be striving to focus on the Object of the tradition, not the tradition itself.
But what of the pagan roots of December 25? Is it true that the church just co-opted a pagan holiday and tried to turn it into a Christian holiday (holy day)? Well, the short answer is: "Yes, indeed it did." But I must ask a question of my own at this point: "So what?" Is it such a bad thing that the church took sun worship and substituted it for Son worship? Is it really not significant that most people now recognize December 25 as Christ’s birthday, rather than Mithra’s? The only people that even know about Mithra or Saturnalia are the Christians who want to denigrate Christmas as being a pagan holiday. The pagan gods have been forgotten and trampled underfoot by the Son of God. Regardless of how you view all of the Exmas and Christmas traditions, the fact that Mithra is a footnote in history and Christ is still remembered—even by those outside the church—is highly significant.
From its earliest beginnings, Christianity has always presented a problem for paganism. In fact, the confrontation between covenant-keepers and covenant-breakers has a long history, going all the way back to the Garden of Eden. We must keep in mind that paganism is always a perversion of the truth. Just as Satan is nothing more than a copycat of the One True God, so paganism is nothing more than a copycat religion of the One True Faith. God owns it all, nothing belonged to Satan in the first place. The dominion that he holds has been granted by God. Consider Jesus’ response when Pilate claimed that he had the authority to have Him crucified. "Jesus answered, ‘You would have no authority over Me, unless it had been given you from above’" (John 19:11). Just as Pilate’s authority was given to him by God, so is Satan’s. Although it comes in all shapes and sizes, paganism is nothing new or novel, it is simply a man-made corruption of God’s revealed truth.
If Christianity was never meant to supplant paganism in this world, why would God have commanded the Israelites to take the promised land from the Canaanites? After all, they were there first weren’t they? If God was so concerned about His people getting tainted by the paganism of the Canaanites, why didn’t He give the Israelites a different piece of land, seeing as how the Promised Land was now covered with pagans? Just as He had humiliated the "gods" of the Egyptians and their human Pharaoh 40 years earlier, God was now revealing to His people that His method of operation is one of dividing and conquering. God made the calendar, just as surely as He made the earth. Christians should not rest until every day of the week is focused on Him and His glory, and not a single day remains that is dedicated to a pagan deity. "We will take every single day from any god that claims any ownership; and whatever we decide to make a global "holiday," will be a global Holy Day."  I find it quite ironic that the same Christians who refuse to acknowledge Christmas, which is at least based on a biblical event, make no such fuss over Thanksgiving, a holiday that has no biblical warrant whatsoever and is based strictly on historical tradition. They also seem to miss the fact that all Christians corporately worship the biblical God on either Sunday (the day of the Sun god), or for others, on Saturday (Saturn’s day). This element of vestigial paganism is conveniently overlooked.
In Acts 17, as the apostle Paul waited for Silas and Timothy to join him, he walked through the city and observed that it was full of idols. Rather than knocking over statues or pretending like they didn’t exist or praying quietly on a park bench, Paul spoke boldly to the academics at the Areopagus about their "unknown God." He reveled to them that what they worshiped in ignorance was in reality the Sovereign and True God of creation. Paul wasn’t bothered that the Athenians were "religious in all respects," in fact, he viewed their religious beliefs as a way to tell them about the One True God. Their paganism was no threat to the Sovereign God Who "made the world and all things in it." Paul conceded no ground to the pagans. Rather, he informed them that they were the ones who had the problem—they were worshiping the creature instead of the Creator.
Some of my readers took issue with my first article, citing the regulative principle or the Second Commandment as grounds for not keeping Christmas. But both of these completely miss the point. I don’t know of any Christians that actually worship their tree. Granted, if this was happening, I would be the first in line to throw my tree into the bonfire. Decorations are not a violation of either the regulative principle or the Second Commandment. If this is the case, there was a whole lot wrong with the tabernacle that God commanded Moses to build, adorned as it was with the silver, gold, and jewels plundered from the Egyptians. There is certainly a danger with traditions; they can easily become idols. But if we learn anything from the iconoclasts of the 16th and 17th centuries it should be this: destroying the idol is easy enough, but destroying the "idol factory" (Calvin’s magnificent term) of the human heart is a much more difficult task. So difficult in fact that no "man" can do it, it takes a "God-man."
Christianity, by its very nature, is a religion of redemption. Christ came "to seek and to save that which was lost" (Luke 19:10), and through Christ, God is "reconciling the world to Himself" (2 Corinthians 5:19) and "making all things new" (Revelation 21:5). Remembering that God created everything, Christianity should not shrink from using everything to praise and honor God. If Christ can reconcile sinful people to Himself, surely He can redeem days of the year. Just because pagans worshiped the sun on Sunday should never preclude Christianity from worshiping the True Son on Sunday. Rather than simply handing over these days to the pagans, Christians need to be taking them back, for the glory of God. Instead of condemning and complaining, we should be rejoicing that the majority of the world actually associates these holidays with Jesus, rather than pagan deities. The pagan origins of these holidays have been all but forgotten, and for that we should be thankful. God is actively reconciling the world to Himself, and if we miss this fact because we are more concerned with what days, months, or times of the year the church has decided to celebrate, we will have missed the entire point of redemption.
 Vance Ferrell, The Fabulous First Centuries of Christianity (Altamont, TN: Harvestime Books, 2006), 417-418.
 Quotation attributed to Bojidar Marinov, source unknown.