I once had a long conversation with a religious relative, and I think it boils down to her not believing that someone can be "moral" without believing that god is watching. Somewhat relevant: Why Did God Create Atheists? There is a famous story told in Chassidic literature that addresses this very question. The Master teaches the student that God created everything in the world to be appreciated, since everything is…
Rust Cohle: "If the only thing keeping a person decent is the expectation of divine reward, then brother that person is a piece of shit. And I’d like to get as many of them out in the open as possible. You gotta get together and tell yourself stories that violate every law of the universe just to get through the goddamn day? What’s that say about your reality?""
[1]: https://en.wikiquote.org/wiki/True_Detective#The_Locked_Room...