The word atheism should always be in lower-case.

It means a disbelief in gods.

I am such an atheist: I disbelieve in gods generally (and not just in one in particular), like I disbelieve in gnomes and dragons and other supernatural and paranormal things.

And the word does not mean anything more than that.

My a-theism means no more to me than my a-gnomism.

The problem comes when one tries to convert lower-case atheism to upper-case Atheism, with the implications of its own belief system.