Live a good life. If there are gods and they are just, they will accept you for your virtue. If the gods are unjust, then they weren't worth worshiping anyway. And if there are no gods, then at least you lived a good life to be remembered by .
2 - dependency on <AFTERLIFE CONCEPT HERE> is due to our fear of death / the unknown combining with religion
We don't know what and if anything happens after death because it is untestable by us for obvious reasons, but some religions still postulate an answer for reasons.
idk, combined with the gloomy atmosphere, it seems like its the only thing keeping OOP safe from a demonic spirit that was summoned during a sleepover using a death ritual