Sermon on the Mount in Context

Seeing the Sermon on the Mount in its native setting—the broader context of Matthew’s gospel—helps us view this sermon for what it’s really about. Scholars and pastors have summarized the theme of the Sermon on the Mount in dozens and dozens of ways over the years, but for me, the most helpful way to simply state the aim of this text is that it is all about the heart.
Jesus’s concern is for the heart of His hearers, of His disciples. God’s desire is to be the king of your heart. Some would say the Sermon on the Mount is about ethics, and I certainly believe there are ethical answers in the Sermon on the Mount. But ethics is the outward manifestation of what is in the heart, and Jesus is well aware of that.
I found John MacArthur’s statement about the purpose of this sermon helpful:
"The thrust of the Sermon on the Mount is that the message and work of the King are first and most importantly internal and not external, and spiritual and moral rather than physical and political. Here we find no politics or social reform. His concern is for what men are because what they are determines what they do."
What you are determines what you do. One of the sayings that is often used in Biblical counseling circles is “We do what we do because we want what we want.” We sin because we want what sin offers, but the teaching of the Sermon on the Mount will plead with us to see that by placing Christ in the place of ultimate authority in your heart is the only way to be truly fulfilled. When we follow our own heart and do what we want to do, it leaves us empty and wanting more. Christ never does! Christ is the good king who satisfies the deepest longings of our heart.\ And that’s what the context of Matthew shows us. Matthew portrays Jesus as the Jewish King who was promised as the savior for God’s people in generations past. That’s why Matthew begins with a genealogy, to establish Jesus’ royal lineage all the way back to King David.
There are certain movies I’m a sucker for and have no idea why. One of them is A Knight’s Tale, and again I have no idea why, but if I see it on, I’m probably going to watch it. It’s not high-quality cinema by any means. It’s based loosely—very loosely—on a work by Geoffrey Chaucer, and it follows the story of a peasant who discovers that his master, Sir Ector, has died in the middle of a jousting tournament. The peasant, William Thatcher (played by Heath Ledger), dons his armor and wins the tournament in his place. Later, he decides to impersonate a nobleman so that he can further compete in jousting competitions. To do so, he enlists the help of a writer to forge noble credentials for him. He’s eventually exposed as a fake, which is exactly what the Pharisees would try to do with Jesus. By the way, it’s good for us to recognize that the root of every sin is denying the Kingship of Jesus.
But His noble credentials were flawless. Matthew points to the authority of Christ in the earliest words of his gospel. It is in Matthew, not Luke, that Magi—these important foreign dignitaries—visit the boy Jesus. And in Matthew 3, we see the proclamation of the King in verse 17 after he is baptized by John, a voice from heaven thunders, “This is my beloved Son, with whom I am well pleased.”

Jesus's first teaching is ripe with the language of the Kingdom—which is going to be extremely important for us to understand the Sermon on the Mount. Look back one page at Matthew 4:17, “From then on Jesus began to preach, ‘Repent, because the kingdom of heaven has come near.’” And in verse 23: Now Jesus began to go all over Galilee, teaching in their synagogues, preaching the good news of the kingdom, and healing every disease and sickness among the people. One thing we should note about this Kingdom: It’s not just a future reality. The Kingdom of God is now. If you belong to Christ, you belong to the Kingdom. Your physical address will change later, from Earth to Eternity, but your citizenship is in God’s Kingdom today.
Matthew introduces Jesus as a king, and His message is good news of a Kingdom. Matthew exposes his readers over and over again to a Jesus who is filled with the authority of a King, the one true King, as a matter of fact. Do you remember the beginning of the Great Commission in Matthew 28:18? Jesus came near and said to them, “All authority has been given to me in heaven and on earth. And it’s this authority that sets Jesus apart as the only one with a message that is worthy of your devotion. Worthy, really, of your entire life. And it is from that place of authority that Jesus will challenge our hearts in the Sermon on the Mount.