Is it rational for, say, Muslims to not celebrate Christmas?

[Rev. Rye]

Technically, it was a pagan holiday called Saturnalia. The first known Christmas celebrations were in 336 AD in Rome. And while there are attestations of Yule happening around the 4th Century AD, Saturnalia was better-established by that point, having been around long enough that it had to be reformed 500 years prior and lasting up to the Christianisation of the Roman Empire. Not saying there weren't some things from Yule that Christians lovingly ripped off stole (caroling, a feast with pork as the main course, or the Yule log), just that there's a bigger influence here.