Oh, we Atheists don't need to pretend that a 'God' doesn't exist. We know one doesn't.
After all, to prove us wrong, to our satisfaction, all you 'God' has to do is to appear to us in hard, solid, physical form that can be seen, heard and touched. Also, to prove he is what he says he is, via demonstrations of his power, again to our satisfaction (and in my case, if that means he has to do whatever I say in perpetuity, so be it).
That's all he has to do. Should be a piece of piss, compared to creating a universe, this world & all the life on it. Amirite?
But to date, he hasn't. Therefore, we Atheists can only conlude one thing:
'God' doesn't exist. Ergo, Atheism. QED.
Unlike the delusion that is fundie 'belief', based on the fairytale that is the Bible.
Now who's the one pretending?