I think you are incorrect. I've done a lot of research in the past couple of days on this topic, and I have come to the conclusion that "atheism" is an extremely general term, and for good reason. It merely requires a lack of belief in the existence of God. This makes sense, as, linguistically, it is defined as "the absence of theism". Thus, anyone who merely lacks a belief in God, whether they are familiar with the idea of God or not, can accurately be classified as "atheist". There are, of course, subcategories of both Theism and Atheism which require more specificity, but I can safely say that "atheists" are those that merely "lack a belief in God".
"Atheism" is often confused as being a system of beliefs or "world view", which it certainly is not. "Strong atheism" is a world-view, but atheism in general is a lack of belief, so many world-views are included in it. For example, there are many "atheistic religions" out there which make up alternate world-views, but are still considered "atheistic", as they lack a belief in God.
I think the most general meaning of the term should be accepted, as both "theist" and "atheist" are extremely general terms which must apply to many different ideologies. I would also argue that, as the word is used by "atheists" themselves (who should be granted the right to define their own beliefs), seems to not signify a belief that God does not exist. In other words, if you asked most of the people who identify as "atheist", they would say that they don't believe in God, and that they don't believe that God does not exist. They just haven't been convinced.