an atheist believes in the non-existence of God and anti-theist is agressively so

Here we go again. That is a total misrepresentation of atheism. Dave thinks there are nice quiet ones and those who actually tell other people why they're atheists (the aggressive ones). Atheists, Dave, don't not believe in God. They don't believe in no God either. There is no engagement. We know there are people who think a God exists (they are very loud about it, so much so that religion occupies a sort of default position in much of the world) and we are simply waiting to see the evidence. Until such times the notions of believers will not impact on our lives (well, it's hard to avoid but we try hard not to let it). Get it right.