I remember enjoying reading the book "After Lives" byJohn Casey, about different conceptions of the afterlife. Obviously, the only possibility of living eternally would be some kind of "biological uploading" carried out across time by a future altruistic civilization, something that seems highly improbable to us today (but which would trump Pascal's wager, by the way).

In any case, these fantasies are above all revealing of the culture of each era. Why did the Egyptians believe in the afterlife and not the Babylonians? Many consider that this belief in divine benevolence implied a certain progression in earthly benevolence.