Every year, around this time, along with the endless “War on Christmas” debates, you’re bound to find a new spin on an old line: that Christians stole December 25 from pagans and turned it into Christmas. Occasionally, this argument goes even deeper, deconstructing various holiday traditions into their roots in various arcane mythologies. Eventually, some articles find nothing at the bottom of the Christmas barrel besides a Frankenstein’s monster made up of different traditions from around the world.
Now, this isn’t totally false. It is definitely true that December 25 is an unlikely candidate for the Jesus’ actual birthday. But to say Christmas is a pagan holiday co-opted by Christians is a little simplistic.
By the third century, Christians were very into trying to figure out the dates of Jesus’ conception, birth and death, but the Gospels didn’t give them many clues to work with. Still, March 25 had become a popular contender for Jesus’ crucifixion thanks to Hippolytus’ “Easter calculation calendar.” A historian by the name of Dr. Sarah Bond has some background on and even some pictures of that calendar here. March 25 was the date of the vernal equinox, so it was pretty attractive as a date of cosmic significance for the early Church. Famous early Christian historian Tertullian was also into the March 25 date.
Now that the Church had selected a date for the crucifixion, they started to work backwards to figure out the day he was born. In ancient times, many Christians believed that the saints lived symmetrical lives — born and dying on the same day. This was an idea they had borrowed from Jewish tradition, which taught that prophets lived “a whole number of years.” The idea that Jesus was conceived on the same day he was crucified took off and, wouldn’t you know it, December 25 is nine months after March 25. You can read more about some of the work that went into this tabulation here and here.
So December 25 was looking good. It was the date of the Roman winter solstice (although not the date of the actual solstice, when the earth’s pole reaches its maximum distance from the sun). This also squared with early Christians’ belief that the life of Jesus would coincide with dates of great, cosmic importance in the calendar. By the time of Saint Augustine, it looked like the December 25 date had been more or less settled, since he references it as Jesus’ birthday “according to tradition.”
It is probably true that Sol Invictus, the Roman sun god, was being celebrated on December 25 concurrently with early Christmas celebrations. But this has more to do with an ancient religious tug of war between which deity got which important dates. The winter solstice was a big deal in the ancient calendar and making it “your” holiday was seen as a pretty big get in the culture war. Some things never change.
But it’s incorrect to say December 25 was an established religious holiday that Christians appropriated. It’s probably better to think of December 25 as a day that held a lot of significance for a lot of different people and Christians were one group in a big wrestling match to dive on the football and claim it for their team.
For an entertaining breakdown of some of the bad history that goes into attributing Christmas to a pagan holiday, check out this piece by Tim O’Neill, an atheist historian who is clearly very irritated by some of the misinformation out there, which he calls “a mangled mish-mash of confused myths, pseudo history and total nonsense.” Merry Christmas!