It's a concept called "Karma". It actually comes from Eastern Philosphy but has been adopted in parts of Western Culture. It doesn't involve "getting money back" which is a concept of the recent retail culture.
We have the concept (roughly) in Western/Judeo/Christian culture which is "Do unto others as you would have them do unto you", the concept being if you treat others well you in turn will be treated well by others.
If someone is an Atheist (Blessed be their Saints Richard Dawkins, Christopher Hitchens, and Charles Darwin..Amen) and believes that they themselves are the highest power that exists, i.e. they look in the mirror and think, "This is it. This is as far as evolution goes" then they will have a very difficult time understanding the concept of "someone looking out for them."
I hope this helps you understand the gist of the story. It is sometimes summed up by the phrase "Karma's a *****, ain't it?" in less philosophical circles.
Oh, I know all about people looking out for me. This may shock you, but I understand concepts like family, loyalty, trust, etc without any help from the spirit world. I also understand the idea of karma, although frankly, I doubt that any supposed higher power would concern himself with the fair market value of used firearms and induce myocardial infarction on those who unfairly profit. I have to wonder what starving kids in Africa did to earn their karma.
Don't waste your time with him, Rick. He probably trampled three old ladies and a baby trying to get to his computer to refute a spiritual comment.
No, but I damn near tripped over my Neil DeGrasse Tyson statue and knocked over my bin full of markers that I use to mark out "In God We Trust" on all of my dollar bills.