This is something I wonder about myself. I don't think I'm ever gonna have kids, but if I did I don't know what I would say when they inevitably asked "what happens when you die?"
Like, I wouldn't want to make up a bunch of stuff about an afterlife or use some religion's version of things, since I don't believe in that myself, but I also wouldn't want to completely horrify my kid by being all "oh there is just nothing. You cease to be aware and that is it." I know that concept freaked me out nearly as bad as the concept of hell when I was little. I guess "make up something comforting" is the lesser of the two evils, but still...
Atheist/nonreligious parents, what do you tell YOUR kids? I am curious to know!