For better or worse, Ricky Gervais is receiving quite a bit of attention recently for being an atheist. In this interview, the interviewer actually suggests that simply disclosing his atheism somehow involves mocking the religious.
As strange as this seems, I suspect that many religious people feel exactly the same way. They take offense when reminded that there are many of us who do not believe in their gods. Somehow, our very existence poses a problem for them.
I've never quite understood this. I can certainly understand how a religious person might find it offensive for an atheist to mock his or her religion, but there is nothing offense in simply saying, "I do not believe that" when discussing matters of religion.