Has anyone, ever, heard anyone of any faith or none object to this? Even Richard Dawkins says it! My Muslim friends wish me Merry Christmas, Mayim Bialik of Big Bang fame wishes her FB followers Merry Christmas despite being an Orthodox Jew!
Surely anyone with half a brain accepts that someone is offering you their good wishes and just returns them? Or, if someone says, "Well actually, I'm Jewish/Muslim/whatever and don't do Christmas.", surely you just say, "Sorry, I didn't realise, have a good holiday."
So why the big deal about the fact that we should/shouldn't say it?
It's just that well known American minority namely Evangelical Christians making a fuss about their "persecution", isn't it?