I’m pretty sure if we had a world where we were all “just” theists, or “just” atheists, we’d find plenty different between our beliefs still to have wars and arguments and prejudice. It probably wouldn’t even sound much different.
I think a world where we all agree we already know everything there is to know, is a scary one. Not that our world isn’t scary. It would just be a different sort of scary.
A better world is one with more open discussion and thought, with more compassion and understanding and sympathy, and with a greater collective sense of altruism and kindness over greed. That’s not theist or atheist, that’s just considerate.
Or a world like the one @Symbeline described… could I skip everywhere in that world??