It is easier to see how the d'fing works to the advantage of the sinner when the sin is breaking God's moral laws.
Anewme, this is something I never understood:
If god's law has been broken then why do humans interfere? Why don't they leave it up to him to love or to punish. Does their belief in god include the belief that he is unable to get it done without the help of humans or a human organisation? Shouldn't humans just live and let live and leave the rest up to their god?
I also never understood the point how d'fing could help someone. The only result of d'fing as far as I can see it is suffering as it cuts people off even their closest relationships. Does pain help anybody? And if feeling pain makes a person change his mind then what is d'fing other than emotional blackmail (that is: I will hurt you to press you into changing your mind)?