Okay, another Christmas post. My treasured anti-Christmas pamphlet says that the Catholics purposely set their feast on the same day as a Roman pagan festival. I grew up believing this myself (though I thought of the culprits as "the early Christians", not "the Catholics"). And I always thought, "So what?" If the pagans had a feast of joy and celebration and light on one of the darkest nights of winter, who wouldn't want to appropriate that? Why not steal their thunder, take their nifty feast, and celebrate our God instead? All's fair in love and feastdays.
But recently I looked into the date of Christmas, and apparently it was originally celebrated on many different dates in different places, and nobody saw fit to preserve a record of why any of those dates were used. There doesn't seem to be a shred of direct historical evidence that December 25th was chosen to upstage Natalis Invicti. It looks like the rumor of this started with some post hoc ergo prompter hoc reasoning, and the story was so plausible it stuck. It might be true, but it's a theory rather than a fact.
Anyway, I assume the pagans had a lot of feast days and so did the Christians. It'd be odd if some of them didn't overlap. Did you know that if you have 23 people in a room, the odds are mathematically in favor of two of them sharing a birthday? But that's another post.