The first and principle characteristic of this mortification of the old man is, a sincere sorrow of heart that we have provoked God by our sins, in other words, true repentance. By the experience of this sincere sorrow of heart you may certainly know that you are converted, no matter, whether this conversion was gradual or sudden. If you wonder sometimes whether or not you are converted, it is well to ask yourself the question whether you are truly sorrow for sin. The true mark of true conversion in this life is not that you are on the mountain-tops of faith and perform many good works, but that you repent in true sorrow after God. How do I know that my sorrow over sin is genuine? There is indeed, a sorrow that is not after God, that is false, counterfeit. It is what the scripture calls the sorrow of the world. The two, however, the sorrow after God and the sorrow after the world, may easily be distinguished. True sorrow after God is rooted in the love of God, while the sorrow of the world is really, principally love of self. The former is a sorrow, that we have provoked God by our sins. It is a sorrow over sin as sin, because sin is contrary to the will of God. The sorrow of the world, on the other hand, is sorrow not over sin, but rather over the evil consequences of sin for ourselves. Counterfeit sorrow over sin really rejoices in iniquity. And it would freely indulge in it, if it were not for the fact that the wages of sin are always death. It is this that the sorrow of the world regrets. True sorrow for sin is a radical break with all sin. But counterfeit sorrow is a break with certain sins, and that only to the degree that their commitment appears dangerous and harmful for the time being. Therefore, godly sorrow leads to life and salvation. Or as scripture puts it, “it works repentance to salvation not to be repented of” (2Corinthians 7:10). But the sorrow of the world works death. The latter really only plays with sin. And the result is always death. But true sorrow over sin is a sure manifestation of conversion.