Dark, I have the feelin that you're trying to claim some special, expert knowledge, about the meanin of "atheism," one which is far too advanced for common knowledge or traditional definitions/distinctions.
But, ya know what? Bertrand Russell, a brilliant mathematician, philosopher and intellectual, and one of the most notorious atheists of the 20th century, fully understood the distinction between an atheist and an agnostic, and presumed that others did too, because the distinction was well-established in both academic and common circles of discourse. He was also aware that different definitions might be appropriate for different audiences.
"As a philosopher, if I were speaking to a purely philosophic audience I should say that I ought to describe myself as an Agnostic, because I do not think that there is a conclusive argument by which one can prove that there is not a God. On the other hand, if I am to convey the right impression to the ordinary man in the street I think I ought to say that I am an Atheist" (Russell)
