If there is a heaven, I'd say God probably gives good people one last chance after they're dead. I'd imagine the conversation God has with the souls of well-meaning agnostics and atheists goes something like this:
God: Hey.
Deadguy: God? Is that you.
God: Yes, it's me. Do you believe in me now?
D: I, uh, am I dreaming?
God: No. Do you believe in me now?
D: Well, uh, how do I know I'm not--
God: Listen. You've lived a decent life. You've helped others and made genuine attempts to make the world a better place. You fell short sometimes, but you always tried your hardest to live up to the standards you'd set for yourself. Because of that, I'm willing to you in, even though you spent most of your life ignoring and/or denying me. But here's the thing-- you've got to believe in me and in the place where you're currently at. We have all of eternity ahead of us, and we are not spending that time on existentialism.