My answer is not from a Christian (you don't want a Muslim or Jewish perspective?), but from a person who has studying spirituality, in all forms, for over half his life.

Heaven and hell do not have to be after death, but are conditions of life. There's no waiting period or divine judgement. If you choose to live unwisely, you will suffer (and so may others). It's a direct cause-and-effect.

This model fits Jesus' "Sermon on the Mount" as well as any religious definition. The Bibles usually call it the "Kingdom of Heaven", but don't say it is obtained after death.