Let's jusst use atheist as I meant it in my original question - someone who does not believe in any god (includes all supernatural "forces" or "superior beings") or gods.
Children are born with very strong beliefs, including the belief in what the adults around them are saying... the tabula rasa has fallen by the wayside. You get your adults' religion(s) the same way you get their language - absorbed like a sponge.
And it's the withdrawal from the brainwashing that makes those who transcend it appear smarter.
Leaving others to be happy in their beliefs is a lousy spiritual principle for the society - would you mean don't speak out against racism, sexism, and other well-held beliefs? I think not.