The hope for continued existence after death is fueled by the sense of incompleteness experienced by everyone. There is always so much more to do. It would not be "just" if one were not allowed to finish up.
Justice is the necessity here. We expect God to make things right at the end. So, from this viewpoint, existence is a testbed for God's "experiments" (us). If we succeed, we graduate post mortem to the mind of God, i.e. we become part of God fully whereas now we are on our own though embedded in His mind (universe) as an autonomous agent.
We expect then to continue after death, to be welcomed into eternity and rewarded for our righteousness in the face of adversity. We may also expect to be punished for our transgressions or "tossed into the pit", i.e. forgotten by God (what could be worse?).
And there's plenty of room. God needn't create an entire universe for each of us. Just use enough of the matter in the universe to "represent" our psyche and run a few "fractal" programs to generate a mockup universe as in Star Trek's hollowdeck. Then, we could experience everything that is good in existence, have fun, then, realizing that we are in fact part of God, remerge with Him thereby adding our little bit of experience to His immense database which is ever enlarging along with the universe.
(See, everything comes back to Star Trek. It's "meaty" ; )