In my opinion, for every bit of good that religion does for the world, it does an order of magnitude more bad. Some religions are more guilty than others, naturally. I'd rather live next to a Buddhist than a couple of mormon missionaries. I definitely don't mind the religions that keep to themselves as much as I mind the ones that try to spread their ignorance and, for the most part, succeed. This is where religion does ultimate harm, by giving people fairy tales to explain things rather than letting us curious humans do what we do best and figure it out ourselves. So much of the future generation has grown up with magical thinking, and comfort in religion. Fortunately, I have noticed that a lot of people seem to drop that stuff once they get to college or start developing their own lives after moving out of their parents place. Which is very good, in my opinion, because I encourage skepticism. The constant interrogation of knowledge and ideas is vital to our progress as a species.

Another non-scientific problem with people not questioning knowledge and ideas is that they also tend to not question people in power. This is...INCREDIBLY DANGEROUS. But I digress.