If someone says "gold cures cancer", everyone and his mom would think he is a nut, unless that's true there's no proof that gold cures anything. The same with religion.

>It's clear that religion exists, it's impossible to find a human culture that lacks it.

So what. A lot of tribes had chamans too, and no magic did work, ever. Look up for "cargo cult" in order how religions works, that's the biggest slap to arrogant American Christian ever, because it works like a huge reality mirror, kinda like: hey, look at that bullshit these Australians are believeing, think for a while on your own bullshit from the Stone Age, because these people with no knowledge of the world (no one in China have heard of Jesus until very recent times (relatively) in the late Middle Ages, so maybe it's religion and god wasn't as Universal as they tought).

The same with Native Americans, no matter North of South. No one have heard of crazy world-wide floods, or whatever.

Also, Bible's great flood was a rehash from the Mesopotapian tales, whose legend maybe date back to the end of the Ice Age.

Ditto with Roman/Greek Gods: if you believe in Zeus/Iupiter, most people will tell you to head an asylum, yet the Judeo-Christian God looks "right". It's just hypocrisy. And fear.