Is it possible that some believers can not even wrap their minds around the idea that atheists really, truly, do not believe in God?

I’m on a Q&A site called Quora and there are a ton of questions about atheism and Christianity. One question that keeps coming up is a variation of “Do atheists feel that God had let them down?”
Is it possible that when folks ask this question it’s because they can’t even fathom not believing in God? Do they think that secretly we do believe in God and are just pretending we don’t? I can only respond with “Do you feel that Zeus has let you down? If you say ‘That’s a silly question!’ then you understand where we’re coming from.”