About The Law*

Matthew 5:17-20 stands as the hinge of the Sermon on the Mount, governing everything Jesus says in the six antitheses that follow (5:21-48). Having just described the character of kingdom citizens in the Beatitudes and their calling as salt and light, Jesus turns to a live question: does his kingdom teaching set aside the Law and the Prophets, the whole of Old Testament revelation? His answer is emphatic. He has not come to abolish (kataluo, to tear down or annul) but to fulfill (pleroo, to fill up, bring to completion) them.

That word "fulfill" carries several senses at once, and Reformed interpreters have generally read them together rather than choosing among them. Jesus fulfills the Law and the Prophets by bringing their predictive and typological trajectory to its intended goal—the sacrifices, priesthood, feasts, and covenant promises all find their substance in him. He fulfills the moral law by rendering the perfect obedience Israel, and Adam before her, failed to render, an obedience that becomes, through union with Christ, the believer's own righteousness before God. And in the antitheses immediately following, he fulfills the law by disclosing its full depth of meaning against the shrunken, externalized reading of the scribes and Pharisees—showing that "you shall not murder" reaches to anger, and "you shall not commit adultery" reaches to lust. Fulfillment, then, is not abrogation but completion: the law's letter is honored even as its true intent is unveiled, and its substance realized in Christ's person and work.

Verse 18 presses the point with striking emphasis. "Until heaven and earth pass away"—a Semitic idiom asserting something close to permanence—not one iota (the smallest Hebrew letter, yod) or dot (keraia, likely the small stroke distinguishing similar Hebrew letters) will pass from the Law until all is accomplished. Jesus affirms the abiding authority of Scripture down to its smallest details. Yet the closing clause, "until all is accomplished," is a crucial qualifier: it ties the law's validity to the unfolding of redemptive history that Jesus himself brings to its climax. This is where confessional Reformed theology has found it necessary to distinguish, as the Westminster Confession does (19.1-4), among the moral, ceremonial, and civil aspects of the Mosaic law. The ceremonial law, given to typify Christ and regulate Israel's worship, is fulfilled and thus set aside as a distinct code once its substance has come; the civil law, given for Israel's particular polity, expired with that state, though its general equity still instructs; but the moral law, summarized in the Ten Commandments and rooted in God's own character, continues to bind all people in every age, precisely because it was never merely provisional. Jesus is not overturning that structure here; he supplies its theological warrant. Nothing in the law's moral substance is annulled—if anything, it is intensified.

Verse 19 draws out the ethical and pastoral stakes. Whoever relaxes one of the least of these commandments, and teaches others to do so, will be called least in the kingdom of heaven, while whoever practices and teaches them will be called great. Jesus binds together doing and teaching; a merely notional orthodoxy that loosens the commandments in practice, or instructs others toward laxity, diminishes one's standing in the kingdom even if it does not forfeit entrance altogether (Jesus assumes such a person remains "in the kingdom of heaven," if least in it). This is a sober word for ministers and teachers in particular, whose handling of the commandments—whether treated as negotiable or as authoritative—shapes the conscience of those under their instruction.

Verse 20 then delivers the statement that governs everything to follow: unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven. This is not a call to stricter legalism, a righteousness of more scrupulous rule-keeping than the Pharisees managed. The scribes and Pharisees were already exacting in external observance; their failure, which the antitheses expose, was that their righteousness stopped at outward conduct while leaving the heart untouched. Jesus demands a righteousness different in kind, not merely degree—one reaching the desires and dispositions from which acts of obedience or transgression spring. Read within the whole of Matthew's Gospel, and within the logic of the gospel itself, this is a righteousness no sinner can produce by self-effort. It is the righteousness Christ himself fulfills in his active obedience and freely credits to those united to him by faith, the very ground on which their entrance into the kingdom rests. What Jesus demands in verse 20, he supplies in the gospel, and what he supplies, he then works out in his people through the ongoing, Spirit-wrought obedience the rest of the Sermon describes.

Taken together, these four verses establish that Jesus' kingdom ethic is not a departure from the Old Testament but its intended fruition—the law honored in its letter, deepened in its meaning, fulfilled in Christ's obedience, and now written, through union with him, on the hearts of his people.

*Content generated with Claude AI