This seems to be a perennial question that I honestly don’t get. There are some atheists out there who are convinced that no atheist ought to be celebrating Christmas. Why the heck not? Christmas hasn’t been a religious holiday for a very long time. It is entirely secular. Christmas trees, Santa Claus, mistletoe, presents and hanging out with family and friends, none of that is religious in the slightest. In fact, even among the religious who might add a couple of religious elements to their celebration, the overwhelming majority are doing it much more for secular reasons than for religious.
So what motivates these people to demand that people shouldn’t celebrate? I suspect that some of it has to do with a general distaste of all things even quasi-religious or having been tainted by the stink of religion, but that’s really a ridiculous reason. Lots of things in modern society have their origins in religion. You can’t just stop living in the modern world because once upon a time, it had religious connotations. And, well, there are some people who are just dicks, who don’t like seeing people having a good time so they make excuses for why nobody should. These are often the same people who make the same arguments about all manner of other holidays, like Easter and the 4th of July. Professional killjoys do not impress, sorry. But beyond being jerks or not having the slightest clue what Christmas has become, what other excuses could they have?
I say go for it. There is nothing at all religious about Christmas. It’s a time to have fun, to be with family and friends and to exchange presents. That’s it. It really doesn’t matter what anyone else does on that day, make the celebration your own and enjoy it. Aren’t atheists supposed to be freethinkers? Why would you allow anyone to ruin your fun? I know I certainly won’t.