If people dont really believe, why do they credit God?

This is one thing I never really understood, and idk if any of u have ever been in this boat so maybe someone can explain it to me. Some people dont really believe in God, but yet when someone they love dies, or someone close to someone they love dies, they say they went to heaven or theyre sure they went to heaven. Or they thank God for things (maybe to appease other people) or they say they are blessed. Im not sayin these people are wrong or dumb or anything, its just something i dont understand.