God does punish sin, but there is no opposition between punishment and forgiveness. The one may be essential to the possibility of the other. Why does God punish sin? Because sin itself deserves punishment? Then how can he tell us to forgive it? Here, then, is the fault with the whole idea: punishment is nowise an offset to sin. Foolish people sometimes, in a tone of self-congratulatory pity, will say, “If if I have sinned, I have suffered.” Yes, verily, but what of that? What merit is there in it? Even had you laid the suffering upon yourself, what did that do to make up for the wrong? That you may have bettered by your suffering is well for you, but what atonement is there in the suffering? The notion is a false one altogether. Punishment, deserved suffering, is not an equal offset for sin; there is no use laying it on the other scale, it will not move it a hair’s breadth. Suffering weighs nothing at all against sin. It is not of the same kind, not under the same laws, any more than mind and matter. We may say a man deserves punishment; but when we forgive and do not punish him, we do not always feel that we have done wrong; neither when we do punish him do we feel that any amends have been made for his wrongdoing. If it were an offset to wrong, then God would be bound to punish; but it cannot be, for he forgives. Punishment is not directly for justice, else mercy would involve injustice. Then it is not for the sake of the punishment, as a thing that in itself ought to be done, but as a means to an end, that God punishes. 

Commentary

by Earle Canty

God does not punish sin for the sake of justice.  He does allow the consequences of sin to fall on the sinner, but that is not punishment for sin.  A sin committed is a finished event.  It is like toothpaste in that once squirted out of the tube, it cannot be taken back (i.e., put back in the tube).  There is no recompense for sin.  Nothing can change the fact that the sin was committed, and nothing can change the effects of the sin.  While punishment can be administered, the punishment cannot change the effects of the sin.  While we may believe otherwise, justice is not served by administering punishment.  Justice administered for wrongdoing is a consequence.  God, in His infinite wisdom and for eternal reasons only He knows, sometimes allows us to experience consequences for sin and other times mercifully allows us to escape the consequences for sin.  {Is 30:18}