I believe the purpose of people on this earth is to be, on a small but meaningful scale, delegated co-creators of this universe. Our environmental freedom and personal free will enables this co-creation.

God who has given us these powers is fulfilled if we use them to grow, prosper, and be happy, and to help those who are not as able as they should be to accomplish these ends. The means to these ends are love, work, creativity and spiritual practice, including worship.

Heaven and hell in the way they are depicted in renaissance paintings are not the most strongly supported concepts in the bible; the English word "heaven" is based on biblical words literally meaning the sky or skies (βασιλεια των ουρανων, the kingdom of the sky, conventionally the kingdom of heaven) and hell is based on odds and ends such as Gehenna, a valley near Jerusalem used for refuse, and Hades, the mysterious name [derivation unknown] of the Homeric Greek god of the underworld.

My interpretation of this metaphoric stretching is that our loving participation in co-creation and/or our redemption via the grace offered by Jesus (which needs to be accepted) allows us to grow in God's direction, as it were; our "treasures in heaven" aren't so much a stack of good deeds as a realized self that fulfilled its mission as a representative of the divine creation.

However, if all we did was to hinder, hurt, obstruct and baffle other co-creators, through acts of baseness, negligence, greed and evil, our effort to knock down the divine creation damages, on a moment-by-moment basis, our portion of immortality as co-creators, so that in the worst case scenario we may get to the end of life with zero or negative credits as co-creators... we then have nothing on which to found an immortality. Hell does not burn us; we have already burned ourselves, made ash of our existence, through pure friction engaged against the loving creation. But our immortality is expended this way... our burntness is forevermore (except by act of grace).

This idea is vividly represented in the C.S. Lewis book novel "The Great Divorce", where people in hell turn out to be flimsy microscopic specks of near-nothing who have to expand enormously and solidify if, after death, they plan to belatedly take up the offer to cross over into the bright, vast and substantial realm of heaven. This is a good book to read if you want to understand the non-medieval heaven and hell.

(NB that when I say co-creation here, I mean on a human scale. I don't imply that humans may become God-like via creation or procreation as Mormonism is alleged to teach.)