I'm an atheist. I have no problem with Christmas.

Christmas is a federal holiday. It can and has been celebrated secularly, with christmas trees and santa claus and such, which aren't remotely Christian. If I was around when they made Christmas a national holiday, I would've had a problem with it. But at this point, it's been made into a secular, federal holiday.

Commercialism happens with everything.

And you have a problem with Christmas because <i>other</i> people get stressed out?

If you don't want to buy people gifts on Christmas, don't.