I have been pondering this question for a while; it keeps me up at night:
Let's say that you are about to enter heaven but behind you are 1, 15, 1000 or infinity numbers of unbelievers doomed to hell behind you except if you are willing to spend the rest of eternity in hell God will let the unbelievers behind you into heaven.
What would you do? The only thing I could think of doing is having to spend the rest of eternity in hell just so they could go to heaven.