I've never understood the controversy. Someone wishing you merry Christmas is no big deal and nor is it an issue if someone doesn't celebrate Christmas. I've had people wish me happy Hannukah, happy Kwanzaa, and happy holidays. My response is usually, "Thank you and you too," or "Thank you and have a merry Christmas." They are mere celebrations assigned to specific days. There's nothing wrong with wishing someone to be happy or merry during that time, regardless of whether or not they engage in the festivities. Really, wishing someone to have a happy or merry day should be encouraged everyday of the year rather than being reserved for the petty exercise of scoring political points.