Do you believe in reincarnation?
Do you believe in heaven?
These are metaphors.

Reincarnation is purgatory.
if one dies with such a fixation on the things of the world that one’s spirit is not ready to behold the beatific vision,then one has to undergo a purgation.one has to be purged clean of one’s limitations.The Limitations are what are called sins.

Sins are besically limited factor that limits your consiousness.