I think that is essentially the truth though - atheism IS just a sort of 'blank slate' position, it is the natural default to theism.
There is no claim of knowledge, no set of idealogies, no dogma - itis just the state of not-being-a-theist.
All of the ideas about 'new-atheists', 'militant atheists', 'hard atheists' etc etc etc are just an attempt to shift the burden of proof by magically transfering it to atheists as a 'burden of disproof', pretending that implicit within atheism is the claim of absolute knowledge of the non-existence of god. Well there's no such thing as a burden of disproof.