This is part of an ongoing series on the Ten Commandments. God’s word reveals to us the laws he requires for living in the world as he has ordered it, and only by living according to this law are we able to flourish and enjoy our creational purpose: to glorify God and enjoy him. This series explores how Christians, whose identity is in Christ and whose inheritance is stored in eternity, should live under and live out the Ten Commandments.
Jesus sits on the side of a mountain, thronged by crowds of the hungry, sick, and poor. He assures them of the blessings that are promised to the meek, the merciful, the poor in spirit, and those who mourn. His teaching, found in Matthew 5–7, is often called the Sermon on the Mount and it is well-known for its juxtaposition to Old Testament law. Repeatedly, Jesus says, “you have heard it said… but I say…” (Matt. 5:21–22, 27–28, 33–44, etc.). Sometimes, this is interpreted as Jesus establishing a new law, and abolishing the Old Testament rules under which the Jews at that point lived. But Jesus himself says, “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” (Matt. 5:17–18). So how are we to understand the Sermon on the Mount? What effect does the coming of Christ have on the law of God established under Moses and summarized in the Ten Commandments?
God’s Law Is Not Contradictory
All law—whether revealed to us by nature or by Scripture—is God’s law, and it is not in conflict with itself. The Ten Commandments, for example, though revealed to us in Scripture, are in harmony with the order seen in natural law. The laws concerning punishments seen in Exodus 21:23–24—“if there is harm, then you shall pay life for life, eye for eye, tooth for tooth, hand for hand, foot for foot”—reflect principles of equity we see in natural law practiced throughout the world, by which societies strive to maintain justice. That’s because both kinds of laws—those given to us in Scripture and those revealed to us in God’s created order—echo God’s character (Rom. 1:19–21). He is the author of them both and they reflect his justice, righteousness, holiness, and goodness.
The Mosaic laws, though not in conflict with God’s natural law, were given to the people of Israel in a very specific context: to set them apart as God’s holy nation, to establish a system for ceremonial religious cleansing, and to reestablish the conditions of Adam’s blessings and fall—in other words, to teach Israel of their sin and their need for a savior. Christ fulfilled this law that Adam failed and that no Israelite could fully obey. This is how he merits our salvation.
The standard of righteous living which Jesus holds up in the Sermon on the Mount is not contradictory to the Ten Commandments or the laws of the Old Testament. It is also God’s law.
Christ Has Come To Change Hearts
But Christ has come not just to fulfill the law—he has come to change hearts. We see this theme of hearts being changed throughout the Old Testament Scriptures, beginning with Moses who said, “And the Lord your God will circumcise your heart and the heart of your offspring, so that you will love the Lord your God with all your heart and with all your soul, that you may live” (Deut. 30:6).
This is what we see in the Sermon on the Mount. Jesus is not concerned with outward behavior only, but with what lies deep within our hearts. In his teaching on adultery, he says, “You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart” (Matt. 5:27–28). No one sees our stolen glances or secret thoughts, but these are stains upon our hearts, sinful blemishes before a holy God. In the same way, Jesus says that being angry with or cursing someone will hold us “liable to the hell of fire,” even if those thoughts or words never manifest in murder or physical harm (Matt. 5:22).
This is an impossible standard for sinful humans to uphold, and the sharp pinpointing of our wayward hearts is convicting. Praise be to God that Christ has fulfilled the law, and his righteousness is counted on our behalf. “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God” (2 Cor. 5:21).
We Are Beholden To The Law of the Kingdom of God
Christ’s perfect work—his life, death, and resurrection—means two very important things for the Christian.
First, we are given new hearts—as promised (Ez. 36:26–27; Heb. 8:10). Paul says we “have put on the new self, which is being renewed in knowledge after the image of its creator” (Col. 3:10) and, because of this, we should put off the sinful ways of the world and put on “compassionate hearts, kindness, humility, meekness, and patience, bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you also must forgive” (Col. 3:12–13). These new hearts are able to obey the law in a way we could not have before.
Second, the eternal inheritance that comes with being saved in Christ changes our relationship to the world. Our citizenship in heaven is accompanied by a new law, one befitting the children of God. Instead of demanding equitable justice (e.g. “an eye for an eye”), the Christian is able to turn the other cheek (Matt. 5:38–39). Christians are able to give generously from few earthly possessions, without recognition, because their heavenly Father sees and has given them an eternal inheritance (Matt. 6:2–3). They are able to speak the truth in love and withstand the accusations of persecutors, knowing they will be rewarded in heaven (Matt. 5:11–12). They are able to love their enemies knowing that they were loved when they were still enemies of God (Matt. 5:9; Rom. 5:8).
None of this contradicts the Ten Commandments or what is revealed in natural law—rather, it reflects the new reality of life in Christ and the promise of heaven. And Jesus calls us to live under this law so that we might be a witness to the new creation to the rest of the world: “You are the light of the world…In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven” (Matt. 5:14–16).
Christ doesn’t change the Ten Commandments. He changes us. His work enables us to live out the law of God by the power of his Holy Spirit, and live freely under the promised realities of the Kingdom of God, in which the grieving shall be comforted, the peacemakers shall be called “sons of God,” and the meek shall inherit the earth.
