I think I've figured out why atheists are so offensive to the religious (and some fellow atheists) and it is because most atheists don't give a fuck about the sacred. When we talk to each other, all sacredness goes out of the window, and we'll talk in a matter of fact down to earth fashion, which is simply blasphemous to any religious onlooker.

Religious people--including some kinds of religious inspired atheists--still retain the sacred in their thinking. This means that certain areas are taboo and subject to special privilege and respect. This explains rather nicely the irrationality of accommodationism and the absurdities of the left in promoting cultural relativism, where cultures and minorities are made 'sacred' from criticism.

Something rather interesting to note: beware of those who hold science as sacred!