So far I've never had an issue with holiday greetings, they say merry christmas, and I'll reply with have a peacefull Yule (and likewise for the other holidays) I've got the occassional confused look from christians with my reply lol but that's about it so far.
I try to never judge anyone elses religion, because I think faith is good to have no matter the form it takes, some of its followers may drive me nuts at times (and that goes with my own faith as well) but as long as no one tries to "convert me" which would end poorly for them, I really don't care :)