看寻正的文章想起来的:
Atheists: what do you say when people wish you "Merry Christmas"? If you go along with it, you've encouraged people to assume that you are Christian and to spread general pressure to act or be Christian. But if you reject the sentiment, you risk returning meanness for kindness--which is not good in itself, and gives Atheists in general a bad name.

I found a solution to this dilemma: I respond, "As an Atheist, I don't celebrate Christmas, but thanks for the good wishes." This way, I can stand up for my views while still being nice to the person who wanted to be nice to me. Give it a try!

A couple of people have asked why I don't just say "Thank you." The reason is that that would not serve the purpose--it would not help strengthen the right to be an Atheist in the US.

http://www.stallman.org/archives/archive-2002.html