This is the ultimate question, overarching all others. The following is my personal, amateur view. The church tells them the answer. This supernatural explanation, or some other mystical version, is accepted by the vast preponderance of the human species. But some of us can't swallow it, because there's no evidence.
Nobody can prove that people continue living after death.
Nobody can prove that people are tortured or rewarded in an afterlife - or that there are any invisible spirits to do the torturing and rewarding. Therefore, we unsure people are doomed to be seekers, always searching for a meaning to life, but never quite finding one. I've been going through it for half a century. Life has a thousand meanings. The best philosophical minds have dug into this for 25 centuries, without success.