One of the reasons (there are many) I think people adopt a religion is to comfort themselves with regard to "bad people" and "good people."
People do things against the society's accepted norm. Murder, theft, rape, or sometimes they just act like complete asses. Without a Great Judge, these people largely get away with their crimes against society. Sure, some get arrested and go to jail. But many people who commit offenses go free. Sometimes because of their behavior they may even fare better than the people they offended.
Further, many people through no fault of their own are dealt a bad hand of cards. Sometimes "good" people get hit by buses or trees fall on them.
Where is their reward for living a good lifestyle? What is the punishment for behaving badly? Without a Great Judge there is no reward or punishment. If you can act like a jerk, behave badly, and mistreat people and get away with it, there isn't any Man Upstairs to make you answer for that. If you live as an outstanding citizen and you are a self-sacrificing person who does everything for everyone and you are murdered at the bank in a robbery, that's it. You're just dead. Just as dead as the jerk when he dies. Your rewards are the same.
This seems unfair so people dream up "good" and "evil" concepts and rewards and punishments to be handed out by some All Powerful Oz to make everything even.
er