Belief in Atonement:

Fear of punishment is, in most cases, the only deterring influence in crushing evil. The pressure of public opinion and legal penalties are the great discouragers of wrong, and wherever they relax their hold, evil begins to crop up. Thus, for example, prostitution, gambling and drinking have been the curse of Christian nations, chiefly for the above reasons. Public opinion in Christian lands is not strong enough to stop evils, while legislation, on its criminal side, is nearly silent on the subject. The fear of punishment in the life to come acts as a deterrent in this respect in non-Christian races; but this can hardly be so with believers in the Atonement. If God could not find any other remedy for the cleansing of human sin than that of sending His own sons from time to time to pay its penalty - since Jesus was only the last of the Pagan Christs who came to give their lives for human salvation - then there is no need of any good action on our part. There are very few of us who pursue virtue for its own sake. It is the reward of virtue, especially seen in its efficacy in counterbalancing the effects of sin, that we fulfill the law and lead a good life. But if the same thing is attainable merely by our belief in the Grace of Blood, few would think it worthwhile to bear the hardships and trials of the life of righteousness. Belief in the Atonement obviates the necessity for action. So it was held by Luther. Though the Romish Church attaches importance to good actions also, yet logically Luther is in the right in his conclusions.