If one has good faith in psychology, then the reason why the the good should be rewarded while the evil should be punished comes from the ideas of reinforcement, punishment, and operant conditioning. Essentially, operant conditioning is increasing or decreasing the probability of a certain behavior due to the effects the behavior has. Reinforcement increases the probability of a certain behavior occurring, and punishment decreases the probability of a certain behavior occurring. Thus, if the good are rewarded, the probability that they will repeat their acts of goodness will increase, and if the bad are punished, the probability that they will repeat their acts of evil will decrease. Overall, the amount of good behavior increases. Humans are naturally hedonistic creatures, seeking pleasure and satisfaction in all that they do. If good behavior is the goal, then there should obviously be some sort of reward that gives humans pleasure and make then want to achieve good behavior. Operant conditioning works because humans strive towards happiness.
Biologically speaking, the meaning of life is to create more life, and humans should act ethically to increase the probability of the species surviving. It is the natural order of things. If everyone were to kill each other, which can be considered as the epitome of evil behavior, nobody would be left to carry on the human species. Even if one person was the ultimate victor over all other humans, it does takes two to create life.
However, this is not the only reason why humans should demonstrate good moral behavior; there is some aspect of personal development involved. Somehow, humans are born with a moral compass that tells one what is right and wrong, what is good and bad, and when there is not somebody, such as God or a friend, to tell one what he or she has done wrong, the moral compass informs the individual, and the individual may punish himself. So, even if one is punished for acting ethically, the moral compass and one’s inner conscience will provide the reinforcement and confirmation that what one did is right. Job, even through his punishment, asserts his goodness because his moral compass tells him so. The aspect of satisfying one’s own moral compass, not one of another, motivates man to act ethically even in face of punishment. Psychology suggests that acts of good behavior decrease with punishment, but innate characteristics of man can override learned behaviors. To listen to one’s moral compass provides the personal development that is qualified as “good”. In simpler terms, good leads to more good and bad leads to more bad. The world needs people to continue on the good, which is the function of the moral compass.
Even though I can speculate as to why humans strive toward good behavior and try to reduce evil behavior, I cannot say why good is good and why bad is bad. The concepts of good and bad are almost like the “givens” of life, similar to the three undefined terms in geometry - points, lines, and planes. One cannot define good and bad without it being circular, and I will not attempt to define them.
So if good behavior is desirable, why does God punish Job, a man who has been good his entire life? It is less of an issue of divine retribution but of divine power. God wishes to maintain his power and wants to assert his power over Job, to tell him that he is just a man living on Earth while God has traversed the path to heaven and death. He brings out the behemoth and the leviathan to show the control He has over the world, that even these huge creatures are under his control. Because God initially punishes Job, he can come down in a whirlwind and tell Job how limited his human perspective is and how unlimited His perspective is. What applies in the human world does not apply in the animal world; God shows Job and his friends that He has allowed the lion to kill other animals because it is part of the natural life cycle, even if it does involve brutally killing other animals and drinking their blood. Human morality, on the other hand, dictates that one shall not kill another. God shows Job the limits of his knowledge by spending a significant portion of his discourse chiding Job for his misuse of imagery and the faults in his reasonings, such as with light and darkness. Humans, unfortunately, cannot know everything, and God wants them to know it.
