Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.Matthew 5:17-18
The history of Israel is a history of struggle against God and his law. No matter where you dip into the Old Testament, you find the same things happening again and again: cycles of sin, repentance, deliverance, complacency, and sin again. From the Aachen’s sin at the conquest of Jericho, to the dull refrain in Judges that the people did what was right in their own eyes. From Eli’s sons taking bribes and perverting justice, to Solomon’s burden of taxation. From the splitting of the kingdom, to the Assyrian captivity of the northern kingdom. From the threats posed by Egypt to the Babylonian captivity. From the ethnic cleansing under Ezra to the revolt of the Maccabees. Even after the Babylonian captivity, when the Jews finally accepted the monotheism of their religion, they still were not able to fully embody the Law Moses had given.
For the Law was intended as a revelation of God’s unchanging nature: his unfailing compassion, kindness, and love. But by Jesus’ day it had become a labyrinth of laws, commentaries, and further clarifications, obfuscating God’s nature and burdening his people beyond endurance. Yet Jesus makes it clear that he has no intention of abolishing the Law or the Prophets. Rather, he has come to fulfill them.
It is easy to understand what it means to fulfill prophecy—though very hard to actually do it. How do you choose your birthplace, for example? But it may be hard to understand what it means to fulfill the Law. One possibility is to simply keep the Law, something Jesus claimed to have done. He challenged his critics to produce one shred of evidence that he was guilty of breaking any Law. Yet if keeping the Law were all he did, his accomplishment would have meaning only for himself alone. But he went further, and made it possible for his followers to have a change of heart so that they would observe the Law not by outward rituals and forms but by representing to the world the real character of God—his loving kindness and compassion. He fulfilled the Law by internalizing it in his followers.
Thus he goes on to redefine murder as hatred and adultery as lust. He urges his followers not to take oaths to certify the truth of what they say, to be generous even to those who try to harm them, and to show care even for enemies. In short, he wants them to be perfect as their heavenly Father is perfect. This is the fulfillment of the Law—an assembly of believers who represent God’s perfect love to a skeptical, watching, hurting world.