Vox Day answers an atheist's question:
The short answer is no, not really, because the self-styled atheist is usually an intrinsically repellent individual for the very reasons that caused him to primarily identify himself on the peculiar basis of one very specific non-belief. The reason that believers, agnostics, and even other atheists all dislike atheists who identify themselves as atheists is because they don't like annoying, dishonest, and literally self-righteous people with social handicaps who reject every objective moral or ethical code. You don't have to be an asshole to call yourself an atheist, but it quite clearly helps. After all, as the 2008 ARIS study showed, the even vast majority of atheists are not willing to call themselves atheists!
While atheism is defined as a belief that gods do not exist,(or sometimes an absence of belief in gods, although in practice it is really just a subset of a materialist philosophy), identifying oneself an atheist is a conscious choice to announce to the world that one's disbelief in gods is a defining and important aspect of one's life. I don't believe in fairies, but I never describe myself as an afairiest because that does not define me in any way, shape or form. When asked about his religion, an atheist could just as easily say that he does not have a religion instead of making a contentious assertion that God does not exist - in fact, most de facto atheists do precisely that - but the self-proclaimed atheist prefers the latter. And therein lies the heart of the answer.