>atheism (which some people mistakenly call Agnosticism) is more
>properly a lack of theistic belief, i.e. it is mere absence, and not a
>positive insistence on the non-existence of a deity.
This has come up before, but it was a while back, and before I became a committed agnostic, so I'd appreciate the chance to go over it again: why, exactly, is it a mistake to call a lack of theistic belief, agnosticism?