First of all, it is unlikely that Jesus was born on December 25. The Bible does not tell us the date of Christ’s birth. The ancient church did not celebrate Christ’s birth at all, choosing instead to focus on His death and resurrection.
It has been suggested that Jesus couldn’t have been born in the winter because the shepherds were outside with their flocks. But the winter is quite mild in Judea so this can’t be ruled out.
In the second century arguments were made for several other dates for Christ’s birth, including April 24 or 25, May 20, August 28 and November 17. But the alternate date that gained the greatest following was January 6. Interestingly, the earliest authors do not mention any sort of celebration on the date of Christ’s birth. In the third century Origen thought that it was sinful to celebrate Christ’s birth as though he was a human king.
December 25 also happened to be the date of the Roman imperial holiday celebrating the birth of the sun god Sol Invictus. Under the Julian calendar the winter solstice was on December 24, so the 25th was the beginning of the return to longer days. Is it a coincidence that the celebration of Christ’s birth took place on the same day? As a practical matter, it made sense for the early church to give believers an alternative to celebrating the popular pagan holiday. It’s difficult to imagine that this did not influence their choice of December 25 as the date to celebrate Christ’s birth.
Another factor was the idea that the Old Testament prophets died on the anniversary of either their conception or their birth. There is no biblical basis for such a theory, but it was a popular idea at the time. Based on the date of Good Friday in AD 354 this lead to the date of December 25 for Christ’s birth. But since Easter is based on the lunar calendar, the same calculation made in other years would lead to a different date for Christmas. Why did they choose that particular year for the calculation? This looks to me like an effort to justify the earlier choice of December 25.
Choosing the date of a pagan feast to celebrate Christ’s birth was not without its dangers. There was the possibility that some Christians would try to combine the two, bringing elements of pagan religion into the church. On the other hand it provided a Christian alternative to a popular celebration. In much the same way today many churches hold their youth group meetings on Friday evenings, in part to provide an alternative to going to parties.
We do not need to know the real day of Christ’s birth in order to celebrate His coming. God has in fact sent His son into the world as our Savior, and we can celebrate that without knowing the exact day. Our own Christmas celebrations are influenced by many other non-Christian cultural factors, but that is a topic for another post.
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