It takes more courage not to believe in gods.

This is because religions promise an after-life, and human's most major fear is fear of death. Give him a pill that takes away fear of death and they will follow you everywhere.

This is why you haven't seen a belief system that makes success without promising life after death.

Really, take a look it, all belief systems that make popular have one main common characteristic. They promise life after death, or more precisely, the destruction of the idea of death itself (in the minds of the followers).

But it takes way more courage to manage without that pill. And actually not courage only, it takes wisdom. It's not necessary to be a struggle to do it after some wisdom is gained.

To say to a 5-year old death does not exist is easy, but to be an adult and a reasonable individual it takes wisdom, strength of character, to not be afraid of death and still not thinking you'll live forever.

Cause after all, wanting (and attempting) to live forever is the ultimate selfish act.