Yesterday we saw how Jesus comes to fulfill the Mosaic law, not to set it aside (Matt. 5:17). Our Lord, being the goal of the Law and the Prophets, by no means intends to do away with them. In fact, as the end of the Law, Jesus reveals the depth of Scripture, making it clear that God’s demands are actually much stricter than the righteousness of the scribes and Pharisees (v. 20).
The meaning of this last point is determined from the practice of the Pharisees and Jesus’ teaching regarding the Law in the life of Israel. Among our Savior’s contemporaries, no one keeps the letter of the Law better than the Pharisees. Few Israelites can imagine outdoing their righteous practice, so exacting is their observation of the commandments. Yet as Christ will show us, outward conformity to the Law’s details, while important, is not enough. Outward observance does not necessarily arise from a righteous motive (Isa. 29:13–14). When inner purity and outward goodness concur, one’s righteousness exceeds that of the scribes and Pharisees. Of course, sinners can never meet this standard, and so Jesus pushes us to see that we all need His righteousness to be reckoned to us in order to be accepted by God (Gal. 2:15–16).
Beginning with today’s passage, Jesus draws a series of antitheses between what has been said and what He Himself is teaching. We must understand at the outset that Jesus is not contradicting the teaching of the Old Testament. What has been “said” (Matt. 5:21, 27, 31, 33, 38, 43) is not what is “written” in the Law (4:4, 7, 10). In these antitheses Christ is giving the full meaning of what Moses originally delivered on Sinai and correcting the sayings — the traditions — that have unpacked the text falsely or incompletely. John Calvin comments: “As the law had been corrupted by false expositions, and turned to a profane meaning, Christ vindicates it against such corruptions, and points out its true meaning.”
Regarding the law against murder (Ex. 20:13), we may think we have kept the commandment if we never kill anyone. Yet hatred provokes all murder, and the anger that produces hatred is actually murder to a lesser degree. Therefore, obeying God requires us to mortify our ungodly anger (Matt. 5:21–26).
Matthew Henry writes that the Pharisees made the fundamental error in thinking that “the divine law prohibited only the sinful act, not the sinful thought.” The unseen sins of the mind and heart are the easiest for us to justify, but God detests our inner wickedness as much as He hates the evil we do before the eyes of men. Seek to reconcile yourself to someone with whom you have been angry unjustly so that your heart and your deeds may be purified.