Not One Jot or Tittle
Matthew 5:17–18 is a key text for interpreting the Sermon on the Mount and the entire gospel of Matthew:
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 say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished.
Here Jesus says that not one iota (jot) or dot (tittle) will pass away from the law. These most likely refer to the smallest strokes of the Hebrew alphabet, indicating that the Old Testament is completely trustworthy, even to the smallest detail. This is consistent with Jesus’ attitude elsewhere. Never do we find Jesus disagreeing with Scripture. Though some have argued that Jesus disagrees with Scripture in the so-called antitheses of Matthew 5:21–48, He explicitly instructs us otherwise in vv. 17–18. Jesus has not come to abolish the Mosaic law (or the Prophets), but to fulfill it. He does not disagree with “it is written” in vv. 21–48, but with “you have heard” (vv. 21, 27, 33, 38, 43; see also v. 31). Jesus critiques mistaken interpretations of Scripture, not the written words themselves.
Therefore, it is necessary to appreciate the abiding truthfulness of the law of Moses because Jesus is the fulfillment of this law (5:17; see Rom. 10:4). Jesus does not nullify it, but comes so that everything in it will be accomplished (Matt. 5:18). He does this through His entire representative obedience. Thus, though the teaching of Jesus is challenging to the core, Jesus did not come to encumber us with impossibly heavy burdens (11:28–30; see 23:4). Only Jesus, the last Adam and perfect Son of God, is able to fulfill God’s law perfectly (3:15) and therefore is able to pour out His blood for the forgiveness of sins (26:28; see 1:21; 20:28).
This does not mean Christians should have no concern to follow God’s law. Christ frees us to obey it. Jesus’ disciples are called to a genuine love of God and neighbor (22:37–40; see 7:21). This is a lofty calling, but Jesus Himself embodied it throughout His life. Through His obedience, Jesus releases us from the burden of trying to earn our salvation. We are to be merciful because of the mercy Jesus has shown to us (5:7; 9:13; 12:7; 23:23; see Hos. 6:6; Matt. 18:33). In sum, the law of God is an abiding witness to the person and work of Christ, and through Him we are able to call this law our delight.