They taught us growing up that the world was intentional, that we used to have some problems as a society but fixed them, that this is all how it’s supposed to be. But that’s the problem, right there — starting from that perspective makes it nearly impossible to notice reality, and how blatantly, obviously unintentional it all is. Farts, snot, periods, appendixes, nipples on men, bad eyesight, polio, tapeworms, body odor, male pattern baldness, buttholes, penises, toejam — honestly, what kind of divine, omnipotent, all-powerful being with supernatural powers would do ANY of that ON PURPOSE? Much less all of it, and infinitely more? This world is visibly grown, not the result of planning and creation. And that changes so much about how we should be responding to it. (Hence: my transition from conservative to liberal and devout Mormon to atheist.)
Every single step of progress is opposed by religion, which should be enough to make more people realize that religion is man-made. The majority of our problems right now could be solved easily, except that there are so many people who believe the problems exist on purpose.