Matthew 5:17. Think not that I have come to abolish the Law and the Prophets; I have not come to abolish them but to fulfill them.
Having given the apostles a serious command and having commissioned them to the ministry, the Lord Christ now takes the next step. He Himself starts salting and shining as an example to teach them what they should preach. He also attacks the doctrine and the life of the Jews, to rebuke and reform their delusions and deeds. As I have said, He does not discuss the great chief doctrine of faith here. Instead, He begins from the bottom by clarifying and commending the Law, which their Pharisees and scribes had completely obscured and distorted. For it is also necessary to clarify and to correct the teaching about God’s commandments.
But it is a sharp and intolerable salt when he attacks and condemns such people as these for not teaching or living correctly, conceding nothing good or right to them—the very best and holiest people, irreproachable, who are teaching God’s commandments and performing holy acts of worship every day. In this way He gave them an opportunity for a shrill denunciation of Him and for the accusation that He wanted to abolish and destroy the Law which God had given. Similarly, the pope and his mob are denouncing us and accusing us of heresy for prohibiting good works. He foresaw this accusation against Him and this interpretation of His teaching. Hence He explains from the outset that He has no intention of abolishing the Law, but had come for the very purpose of correcting and confirming the teaching of the Law in opposition to those who were weakening it by their teaching.
Such a clarification was necessary on account of their great renown and on account of their excellent reputation. If anyone took it upon himself to denounce them, they would immediately create a fuss and throw dust in his eyes by insisting that they alone are the people of God, with so many prophets and holy fathers: “Who are you, that you should be wise enough to criticize everyone else, as though our fathers and we had all been wrong, we who have and preach the Law of God?” That is exactly what the whole world is yelling at us now. It accuses us of condemning the holy fathers and the entire church, which is infallible because it is governed by the Holy Spirit. “Because you are criticizing our teaching and life,” they say to Christ, “this is an indication that you are condemning the Law and the Prophets, the fathers and the whole nation.” To this Christ answers: “No. Certainly I have no intention of destroying the Law or the Prophets. I am more respectful toward them and more scrupulous and serious in my observance of them than you are, so much so that heaven and earth could pass away before I would let an iota or a dot perish or be useless. Indeed, I will go on to say that if anyone despises or departs from the very smallest commandment in his teaching, he will be thrown out of the kingdom of heaven for this minor offense, even though he might keep everything else. Thus we are in agreement that Moses and the Prophets must be taught and enforced rigidly, but the issue is this: since both of us have the obligation and the desire to teach the Law, it has to be determined which of the two sides is correctly citing and interpreting Scripture or God’s Law. This is the point at issue, and here I have to salt and denounce. With their glosses the Jews have distorted and corrupted the Law, and I have come to set it straight.” Right now, too, both we and our opponents, the pope and the other sects, are appealing to the same Scripture and laying claim to one Gospel and Word of God. We have had to attack the doctrine of the pope, which has corrupted Scripture for us with its stench and filth.
He is not denying that they are God’s people and that they have the Law, the fathers, and the prophets. Nor are we condemning or denying that under the pope there were Christians or Baptism or the Gospel, but we are saying: “What we have is the right Baptism and Gospel.” We protest against having to accept and approve the way they smear it all up, the way they interpret and distort it by defiling the pure doctrine with the foul and wormy, yes, the demonic addition of their cowls, tonsures, indulgences, purgatory, and sacrificial masses. This is where we set to work with our salting, to get rid of this stench and to fumigate it. So it is clear that the very dissolvers and destroyers of Law and Scripture decorate themselves with lovely titles like “Scripture” or “Gospel” or “Christian Church” and that under this pretext they have imported their maggots and corrupted everything and made it useless. And then they yell at us for attacking the Christian Church, the holy fathers, and good works!
Now He says: “I have come not to destroy the Law but to fulfill it.” That is: “I do not intend to bring another law or a new law, but to take the very Scriptures which you have and to emphasize them, dealing with them in such a way as to teach you how to behave.” What the Gospel or the preaching of Christ brings is not a new doctrine to undo change the Law, but, as St. Paul says (Rom. 1:2), the very same thing that was “promised beforehand through the prophets in the Scripture.” From our opponents, therefore, we accept the very same Scriptures, Baptism, and Sacrament that they have; and we do not intend to propose something new or better. All we are doing is insisting upon their proper preaching and administration and upon the elimination of anything that does not harmonize with them.
St. Augustine interprets the word “fulfill” in a twofold manner.25 According to him, “fulfilling the Law” means, first, “supplementing its deficiencies” and, second, “carrying out its content in works and in life.” But the first interpretation is mistaken. All by itself, the Law is so rich and perfect that no one need to add anything to it; for the apostles themselves had to prove the Gospel and the proclamation about Christ on the basis of the Old Testament. Therefore no one, not even Christ Himself, can improve upon the Law. What can you make up or teach that is higher than what the First Commandment teaches (Deut. 6:5): “You shall love God with all your heart”? He does indeed go beyond Law and doctrine when He gives His grace and Spirit to enable us to do and keep the Law’s demands, but that is not “supplementing” the Law. And so He is not talking about that here, but about that fulfilling which takes place through teaching; similarly, by “abolishing” He does not mean acting contrary to the Law, but teaching in such a way as to subtract from it.
What is said here, therefore, is not different from what St. Paul says (Rom. 3:31): “Do we, then, overthrow the Law by this faith? By no means! On the contrary, we uphold the Law.” He does not intend to bring another doctrine, as though the former one were no longer in force. He intends, rather, to preach it, to emphasize it, to show its real kernel and meaning, and to teach them what the Law is and what it requires, in antithesis to the glosses which the Pharisees have introduced, the shells and husks which they have been preaching. Similarly we can say to our papists: “We have no intention of abolishing your Gospel or of preaching any other way. All we want to do is to clean it off and polish it, as a mirror that has been so darkened and spotted by your filth that only the name ‘Gospel’ is left, but nothing by which anyone can see.” Thus the Jewish teachers retained the text of the Law, but they so corrupted it with their additions that neither its proper understanding nor its proper use was left.
Luther, M. (1999, c1956). Vol. 21: Luther's works, vol. 21 : The Sermon on the Mount and the Magnificat (J. J. Pelikan, H. C. Oswald & H. T. Lehmann, Ed.). Luther's Works (21:67). Saint Louis: Concordia Publishing House.