Sin is a wrong overt action. It is a trait of inner character. Sin is an evil deed. It is willful violation or neglect of duties. It is either the commission of wrong deeds or omission of right deeds. We are never lacking in good intention. But we may not have the strength of will to convert them into overt acts. Bad intentions also are frustrated by infirmity of the purpose and do not issue in evil deeds. And thus they are harboured in the mind and stain the inner character. If they issue in deeds, sometimes they exhaust themselves. Thus a good intention is not so good as a good act, while a bad intention is on the whole, worse than a bad act.
Crime, on other hand, is said to be committed, when the laws have been violated. It involves punishment by an objective authority such as State or government, appointed court of law. Crime thus refers to the offence against society, which are recognized by law and liable to be punished. Ingratitude e.g. would be a sin and not a crime. Murder or stealing is a crime. That is why T S Eliot writes in his ‘Elder Statesmen’, “Where as crime is in relation to a law, sin is relation to a sinner”.
A crime ought to be punished. One who suffers wrong is not degraded. His soul is not hurt by it. But one who does wrong lowers himself in the scale of moral perfection. A man is rewarded for his good deeds and similarly a man should be punished for his evil deeds. If a criminal has deliberately broken the moral law, the majesty and the authority of the moral law demand that he ought to be punished. “Punishment is the just retribution for deliberate breach of moral law”. Wrongness of the act is brought home to the criminal by punishing him. This is the ethical justification of punishment.