After seemingly endless discussions of this subject with theists, I have become convinced that the root of the problem lies in the all-encompassing nature of religious beliefs. To the theist (or at least many of them), belief in God is the center of life. It informs their views on ethics, morals, cosmology, history, and virtually everything else. They literally cannot comprehend that a lack of belief in gods doesn't fill the same roll in the atheist's life that belief does in the believers. Hence such meaningless concepts as "atheism is a religion" and "lack of belief is a belief".
Atheists as individuals have beliefs about many or all of the same subjects as theists, but those beliefs are informed by the things we do believe in, not the things we don't. It's kind of a turf war. Theism tries to claim concepts like ethics or morals as their turf, and then by extension claim that lack of theistic belief must therefore constitute the basis for the beliefs of others regarding such subjects.
Capt.
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