You understand perfectly what they're talking about, or you understand perfectly that they're talking hippie bullshit?

The Greek prefix "a-" does indeed mean without. What it does not mean is anti. Atheists of good will don't really go round asserting things. They go around advising what it is intellectually erroneous to be asserting. Generally speaking, we do a lot of indulgent smiling and shrugging. We haven't really got anything to assert. A good atheist will always tell you that he or she fully respects the beliefs of religious people. Why anyone should believe in total nonsense is beyond us, of course, though we understand about suspension of disbelief when it's used to enjoy good films or operas (which often have the silliest possible storylines), and when we are firing up the imaginations of our children (we do have a responsibility to ensure that, ultimately, they know what's myth and what's truth, a responsibility which, sadly, is routinely shirked by people who raise their children within religious faiths).

I don't assert the non-existence of God. I don't do it because I don't know whether there's a God or not. If you think that disqualifies me from being an atheist, tough. You don't know whether there's a God or not. Pete doesn't know whether there's a God or not and Joe Offer doesn't know whether there's a God or not. The Pope doesn't know whether there's a God or not. Everybody's an agnostic or nobody's an agnostic. I prefer the latter, because no human ever born knows whether there's a God or not. It's just that some of us are humble enough to admit it. A priest or brother in a Catholic school isn't humble enough to admit it, otherwise he wouldn't force the children in his care to chant prayers which assert certainties. Agnosticism is a useless word. Atheism is not a useless word but it's a bloody annoying one, because it defines perfectly innocent people in terms of religion, a human invention, and that isn't right. But I still am one. I can live with it.