If atheists are right, they die and worms eat them. By discussing the afterlife at all, we’re assuming Christians are right, just for the sake of argument. And not believing in God doesn’t affect the question of his existence one way or another, just as not believing in gravity doesn’t affect its existence. So they obviously still repent to God.
I still say real atheists have a better chance, since calling oneself a Christian involves an obligation to accept certain propositions as true–including a) there is a God and b) Jesus is him. Atheists, obviously, do not hold this is true, and won’t be held accountable for precepts the Revelation of which they didn’t believe in.