Augustine of Hippo

Paul says this so that, when something might be done with either good or bad motives, we should leave the judgment to God and not presume to judge the heart of someone else, which we do not see. But when it comes to things which obviously could not have been done with good and innocent intentions, it is not wrong if we pass judgment. So in the matter of food, where it is not known what the motive in eating it is, Paul does not want us to be judges, but God. But in the case of that abominable immorality where a man had taken his stepmother, Paul taught us to judge. For that man could not possibly claim that he committed such a gross act of indecency with good intentions. So we must pass judgment on things which are obviously wrong.