Jews and Christians share many things in common. The God of Abraham, Isaac, and Jacob is the God of Jesus Christ (Acts 3.13). The promise God made to Abraham to bless both his descendants and the world through them (Gen. 12.2, 3) finds its fulfillment in the salvation offered freely to Jews and Gentiles alike (Rom. 1.16). And we have the Old Testament in common, although Jews do not believe there is anything “old” about it. (And neither should we.)

And yet, we have many differences too. We believe that God is a Trinity of Persons: one God eternally existing as Father, Son, and Holy Spirit. They do not. We believe that Jesus is the long-expected Messiah the Prophets spoke about. They do not. They believe that Sabbath keeping, a kosher lifestyle, and male circumcision are necessary elements of a God-fearing lifestyle. We do not. Together, we interpret and apply the very same Scriptures we hold in common in different—even mutually exclusive—ways.

How did this situation come about? Jesus! He explains both what we hold in common and what makes us different. And these points of commonality and difference are on vivid display in the longest section of the Sermon on the Mount, the section dealing with “righteousness” (Matt. 5.17–6.34). Matthew 5.17–48 deals with righteousness in our dealings with other people. Matthew 6.1­–34 deals with righteousness in our relationship with God. In both passages, Jesus differentiates his followers’ “righteousness” from that “of the Pharisees and the teachers of the law” (Matt. 5.20).

But he begins with a statement of commonality: “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. I tell you the truth, 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. Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven. For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven” (Matt. 5.17­–20).

We Christians have become so accustomed to Paul’s statement that we are “not under law, but under grace” (Rom. 6.14, 15) that we ignore the law. More generally, we neglect reading the Old Testament. Doing so is not Christian, though, at least not if Christianity is defined by Christ’s example. The Old Testament Law and Prophets are our Scriptures, which Jesus came to fulfill. If we ignore them, we ignore him.

So, in this week’s devotionals, I intend to look very closely at Matthew 5.17­­–20 to see what they teach us about who Christ is—and what it means to be a Christian.