I was watching a documentary in which the director was interviewing people who lived hunter/gatherer lives. He asked someone what they thought happened after death, and the response was that they put the dead bodies in the cave. Despite the director's best efforts to clarify what he meant, the man responded that the bodies go in the cave and looked at the director like he was stupid for continuing to ask the same question.
They had no concept of an afterlife despite being a continuous ethnic group for longer than agriculture has existed. For all that time until today there was no need for promises only granted after death. It's disturbing to me how important that promise is for most of us, otherwise the world we made for ourselves could be intolerable.