You lose either way. Saying "Merry Christmas" isn't neccessary, but try to bridge the gap with a "happy holidays" and you're slammed by the "political correctness omg dumb" people. I read in Newsweek that 31% of Americans are offended (yes, offended) by the term "happy holidays". What the hell is wrong with everybody?
No group of people should be offended by a generic 2-word formality. Say whatever you want. Whatever somebody says to you, just grin and say "you too!" . It really isn't that hard.
