My story! I am an Ex-Muslim, became and Atheist. I was visited by an Angel of God.

[robvalue]

That's right. Believing in any fairy tale could "help" you, if you believe you have an imaginary friend constantly cheering you on and saying how great you are, it may give you more confidence. But at the end of the day, people get where they are through their own actions, and sadly often give the credit away to non-demonstrated things.

The same effect can be had without having to believe fake things, by working on your own confidence. You could visualize people cheering you on, without having to believe they are real.

It's when such a belief causes you to make a bad decision, that is when it costs you. And the further away your internal model of reality is from actual reality, the more likely you are to make a bad decision. This affects not just you but also those around you.