Why Obedience to Jesus Trumps All: Thoughts on the Sermon on the Mount

By Craig S. Keener

In the Sermon on the Mount, Jesus summons us to stake our hearts on the reality of God. Both Matthew and Luke report much of this sermon, and James is among New Testament writers who echo it. In Matthew’s version, Jesus offers ethical instruction more radical than the law of Moses. We can see this in the opening section of Jesus’ teaching—especially Matthew 5:17–48—and it continues through the rest of the sermon (6:1–7:28).

Jesus and the law

Jesus cares not only about what we do but about who we are on the inside. Pharisees agreed with such ethics in principle, just as Christians do today. What they lacked, however, was the transformed, born-anew heart of one who receives the kingdom like a child (18:3; 19:14).

Jesus’ demands are more radical than those in Jewish law. Jesus explains that he did not come to abolish the law but to fulfill it (5:17). To illustrate this point, he says not even the smallest letter will pass from the law (5:18). His hearers would have understood this way of speaking; other Jewish teachers used to tell stories about the smallest letter protesting when removed from the Bible!

Jesus warns against neglecting even the least commandment (5:19). Some of his contemporaries similarly insisted the reward was the same for the least commandment as for the greatest. This was just an emphatic way of saying that we dare not dismiss the importance of any of God’s commandments. Yet Jesus goes beyond his contemporaries, warning that the righteousness of even the scribes and Pharisees was insufficient for the kingdom (5:20).

Among the Pharisees, teachers added extra rules to help guard against breaking commandments; they called this a “fence” around the law. But Jesus approaches the law differently, looking at what its principles invite from a God-devoted heart. Six times in 5:21–48, Jesus quotes the law and then explains that God wants more from us than what it says on the surface. For example:

• The law says, “You shall not kill” (5:21, quoting Exod 20:13; Deut 5:17). But Jesus says, “You shall not want to kill” (Matt 5:22). 
• The law says, “You shall not commit adultery” (Matt 5:27, quoting Exod 20:14; Deut 5:18). But Jesus says, “You shall not want to commit adultery” (Matt 5:28) or betray your spouse by unfaithful divorce (5:32).
  

Jesus cares not only about what we do but about who we are on the inside. Pharisees agreed with such ethics in principle, just as Christians do today. What they lacked, however, was the transformed, born-anew heart of one who receives the kingdom like a child (18:3; 19:14). 

Jesus valued God’s purpose in the law. The same law that said “you shall not commit adultery” also warned “you shall not covet” (Exod 20:17; Deut 5:21). In the Greek text of Matthew, Jesus uses the same verb for “covet” when he warns against lusting after someone. 

Hyperbole in Jesus’ teaching

Jesus often seizes our attention with hyperbole—the practice of overstating something for rhetorical purposes. 

While calling someone a “fool” can merit hellfire (Matt 5:22), Jesus calls opponents fools when appropriate (23:17). Are all remarriages actually adulterous unions that should be dissolved (5:32)? Probably this idea is no more literal than the suggestion that those guilty of lust should tear out their eyes (5:28–29).

In Matthew, Jesus makes exceptions for the innocent party in a divorce. But if the innocent party is no longer married in God’s sight to their guilty spouse, how can even the guilty spouse remain married to the innocent one? For both lust and divorce, the literal point is that we must radically embrace marital faithfulness as a sacred commitment before God. Believers cannot control the choices their spouse makes, but for their own part, they must choose faithfulness.

Jesus’ final three examples also address the heart.

• The law prohibits breaking vows, but Jesus demands such integrity that oaths become superfluous (5:33–37).
• The law allows legal retribution that matches the offense, but Jesus requires nonretaliation (5:38–42).
• The law might allow hatred of enemies, but Jesus demands loving even one’s enemies (5:43–48).

Here, too, Jesus uses hyperbole. For example, relinquishing both outer and inner garments (5:40) will leave a person naked. Likewise, giving to everyone who asks (5:42) would quickly leave someone destitute.

Despite hyperbole, however, Jesus actually demands more than what he states, rather than less. He offers merely examples; lust does not become permissible simply because both parties are single, or because a woman rather than a man is doing the lusting (5:28). Someone who wants to limit obedience to these examples must face the summary in 5:48: we should be as perfect as our heavenly Father. When God is the standard, all of us have room to grow. Beyond examples, the law’s heart is treating others as we desire to be treated (7:12)—loving others as if they were ourselves (22:39–40).

Look to God alone

Jesus warns us not to be hypocrites—people holier on the outside than on the inside (6:2, 5, 16). Where religion is accepted, people can sometimes undertake religious actions to impress other people rather than God. In fact, they can practice religion as if God does not really exist or see their actions!

It’s hypocrisy to neglect our devotion when God alone is watching. Although we can do good works so others will see them and honor our Father (5:16), we dare not do them so others will honor us. Otherwise, approval from other people is our reward, and we will not have any from our heavenly Father (6:1).

It’s hypocrisy to neglect our devotion when God alone is watching. Although we can do good works so others will see them and honor our Father (5:16), we dare not do them so others will honor us. Otherwise, approval from other people is our reward, and we will not have any from our heavenly Father (6:1).

Jesus illustrates this principle with three examples, again using hyperbole:

• Don’t make a scene when you donate charity (6:2–4).
• Don’t draw attention to yourself while praying, like hypocrites do (6:5–6), or try to persuade God to listen as if your Father is not already there (6:7–13). (To this theme he adds: forgive others, trusting God to have your back.)
• Don’t make it obvious that you’re fasting (6:16–18).

Similarly, we should neither put trust in possessions nor depend on them (6:19–34). We should seek God’s kingdom, use our possessions only as stewards for the kingdom, and trust God to supply our needs. We can trust our Father to care for us (6:11, 25–30; 7:9–11). Although we must discern false prophets (7:15–23), we must not set ourselves in God’s place as the judge of others (7:1–6).

Christ-centered ethics

Jesus does not discuss ethics in purely human terms. He grounds ethics in the reality of God and in discipleship to himself. It is not sufficient even to call Jesus Lord or act in his name; we must obey him (7:21–23). Because Jesus and his kingdom are worth everything (13:44–46), his followers must value him above job security (4:18–22), residential security (8:19), family and social expectations (8:22; 10:37), possessions (6:19–20; 19:21), and life itself (10:38–39; 16:24–25).

Not surprisingly, then, this sermon climaxes with the warning that only those who build on Jesus’ words will survive the day of judgment (7:24–27). In a familiar Jewish parable, those who build on the foundation of God’s law withstand the storm; Jesus, however, applies it to his own words, which are just as authoritative as God’s law. 

Like the crowds, we should marvel at Jesus’ teaching (7:28). We also must take it to heart.

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Study Matthew further with Craig S. Keener in The Gospel of Matthew (A Socio-Rhetorical Commentary) and Matthew (The IVP New Testament Commentary | IVPNTC)

This post originally appeared in the January/February 2020 edition of Bible Study Magazine.

The headings and title of this post are the additions of the editor. The author’s views do not necessarily represent those of Faithlife.