I'm sure this has been talked about before, but I always find it fascinating when someone considers themself a Jewish Atheist, like I do. Cultural vs concept I think, but I rarely see other religions denoted as such. Catholic Atheist, Mormon Atheist, Christian, Hindu, etc...
Perhaps because outside of the Jewish faith most people consider Judaism a religion and nothing else, therefore a Jewish atheist is to most people like meat eating vegetarians or insisting on referring to your cat as "dog".
In all other religions, it is impossibility to refer to yourself as such, and to most non Jews, the idea of a Jewish atheist is simply a ludicrous oxymoron.