What is Atheism?

[SteveII]

But why does assessing a 'burden of proof' have anything to do with it. You could have never heard any proof (nor want to) and have a belief there is not God.

Because atheism is a response to a claim, literally a-theism.  It's a response to the claim that a god(s) exist.  Any claim that makes assertions about reality has a burden of proof.  I simply don't think that the claim of theism has met this burden - ergo, I'm an a-theist.

You won't find me anywhere on this forum making the claim "There are no gods" because I don't think I'd be able to (or anyone, really) meet that claim's burden of proof.

But just because someone avoids saying the claim does not mean they do not believe it and continually imply the claim by their choice of words and attitudes when discussing the subject. 

Consider the difference between saying 

1. "I believe there is no gold on the moon" and 
2. "I do not believe there is gold on the moon"

If you have no opinion on the matter, then you believe 2. But the problem is that everyone here does have an opinion on the matter (because they have assessed the proof offered and found it lacking) so believes 1.