Confusing the law and Gospel contributed to a medieval piety that maintained that while we enter into a state of justice by grace, we then need to satisfy God’s justice by works. Martin Luther found that idea suffocating. Even our best works lack perfect intentions. Christians know this. So the judgment of God became a fearful thing to Luther and others with sensitive consciences.
But upon reading and teaching Scripture, Luther re-discovered Paul’s emphasis on the law and Gospel. In the Gospel itself, God reveals his righteousness (Rom 1:17). That meant (and means) that, in Christ, the righteousness of God clothes us at the moment we believe. We do not need to merit God’s approval. He accepts us in Christ forever. Good works then flow out of a good heart—a good tree produces good fruits.
The law, on the other, hand condemns.
When Luther speaks of law and gospel, he can use these terms to describe a biblical pattern of commands and promises. In his The Freedom of the Christian, Luther explains “that the entire Scripture of God is divided into two parts: commands and promises.” Luther’s close associate Philip Melanchthon will say more directly, “All of Scripture is either Law or Gospel.”
The law refers specifically to the Law of Moses but overlaps conceptually with other commands of God in Scripture. The Gospel refers specifically to the good news about Jesus Christ, but Scripture often contains promises of the gospel (e.g., Gen 3:15).
For Luther and the scriptural authors, the law carries the basic functions of revealing sin (Rom 7:9) and increasing sin (Rom 5:20). It also restrains evil. Luther commends it then when used properly “first to bridle civil transgressions, and then to reveal and to increase spiritual transgressions.”
In the end, the law is meant to show us our need for the Gospel. “For the Law has its terminus,” writes Luther “defining how far it is to go and what it is to achieve, namely, to terrify the impenitent with the wrath and displeasure of God and drive them to Christ.”
This, in part, explains why Luther does not see the Mosaic Law per se as having ongoing force over the Christian: “It is no longer binding on us because it was given only to the people of Israel.” He certainly sees the Ten Commandments as abiding moral laws since, however, they are “written by nature into their hearts.”
And he thinks Moses gives wise laws to Israel. Although they are not binding upon anyone, these laws model wisdom and justice. The reformers will later explain that the ceremonies and civil aspects of law served Israel in their specific location in time and place and as such is no longer binding upon people today as law. Melanchthon too can say that “the entire Law has been abolished.” Luther holds to the same view.
And for Luther, in the new covenant, the Gospel promise means that God gives us the Holy Spirit so that we can live righteously without the law’s condemnation and not for the sake of meriting God’s acceptance of us—but simply because it is good to do so, it serves our neighbour, and it pleases God in a non-meritorious sense.
Since Luther frequently cites and uses the Old Testament, this does not mean he in any way relegates the law to some forgotten realm. No. Luther rather puts law in its God-given place. It threatens and restrains so that we better understand the Gospel of freedom.
For Luther, the gospel of grace saves us apart from any works of the law. As his colleague Philip Melancthon wrote, “The Law shows the disease, the Gospel the cure.” The Bible is full of law and gospel, command and promise. The New Testament is not simply gospel, while Old Testament law. As Luther says of the Old Testament: “Here you will find the swaddling cloths and the manger in which Criest lies, and to which the angel points the shepherds [Luke 2:12].”
As a general tendency, Luther admits that the Old Testament emphasizes law, while the New Testament highlights grace. But the Old Testament still promises the Gospel (e.g. Gen 3:15), while the New Testament conveys commands to help us restrain the flesh. In this sense, the categories of law and gospel and the broader categories of command and grace help us make sense of how to read the whole Bible.
The Gospel is God’s approval of us on the basis of God clothing us with the righteousness of Christ. In his 1520 treatise, On The Freedom of the Christian, Luther uses the analogy of marriage. When a bride marries a bridegroom, everything she has belongs to him; and the bridegroom shares with her his whole life. In the Gospel, we give up entirely our sin and Christ gives entirely his righteousness. We are then by this union justified by faith. An alien (foreign) righteousness becomes ours by faith.
Christ is our righteousness. Any works done after our justification matter, according to Luther, because it pleases God (not salvifically) and because we need to love our neighbours. A good tree, he avers, produces good fruit. The law does not need to threaten us anymore. The moral law, however, still guides us in our Christian walk. Hence, Luther will include the Ten Commandments in his catechisms.
Third-use of the law
Luther then had a positive place for law by the very fact that the Ten Commandments stand in central place in his catechism. Other reformers, John Calvin, in particular, would advocate for a more precise way of describing this positive use of the law called the third use of the law.
While the ceremonial and civic aspects of the law have expired since they aimed to preserve charity and justice among Israel and also point to the need of a new law, the Ten Commandments principally correspond to God’s moral law. Everyone knows that murder is wrong, even if they do it. That is part of the fabric of nature because God made nature. It then has a moral order.
These sorts of laws no longer fall upon us as laws under the mosaic law, but as eternal standards of God. Hence, law in this sense has no meritorious use for a Christian but rather a sapiential use—it is wise and good to study God’s law to understand what moral principles we ought to emulate.
Luther observed a biblical pattern, and he pressed into the notions of grace and command to help Christians understand the Gospel. The freedom of the Christian means that God grants us all things for our salvation freely. The duty of Christian means that while we live in the flesh, we must serve others and those in authority over us. Scripture stands as the authority over both these overlapping spheres of life.
But confusing law and gospel creates a massive problem for Christians. It makes the law of Moses into a “must” for Christians even though Christ set us free from the yoke of the law. “For unless the Gospel be plainly discerned from the law,” writes Luther, “the true Christian doctrine cannot be kept sound and uncorrupt” (“Galatians” 1962, 145).
The Gospel bestows the Spirit of freedom to the Christian so that we can obey from the heart. The law is not then thrown out but put in its place. Paul explains, “But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law” (Gal 5:22–23). Paul commends and even commands good behaviour, but the motivation is grace and the power to obey is Spiritual.
To rebuild the wall of the Mosaic law simply makes one a transgressor of the law (Gal 2:18). It also makes one a legalist. Peter explains, “Now, therefore, why are you putting God to the test by placing a yoke on the neck of the disciples that neither our fathers nor we have been able to bear?” (Acts 15:10). In the next verse, Peter defines the difference that Christ brings, “But we believe that we will be saved through the grace of the Lord Jesus, just as they will” (Acts 15:11).
Peter lays the law of Moses side-by-side with the grace of Christ. He tells us that that the law is a yoke that no one can bear. But the Gospel is grace which we can receive. In Paul’s idiom, “For freedom Christ has set us free; stand firm therefore, and do not submit again to a yoke of slavery” (Gal 5:1).
Some medieval piety attempted to yoke Christians to human customs. But when law enters as a means of staying within a state of justice, in effect the law becomes the means by which one maintains their salvation. Instead, the Gospel sets us free from such a view. It liberates us from having to obey human customs or the law of Moses to remain in a state of justice. The law is a good guide for the Christian life, but a terrible master; the Lord Jesus sets us free, not law.
Between legalism and antinomianism lies Luther’s Gospel of grace because he rightly discerned the basic pattern that Paul and the Scriptural authors taught. Scripture, the Law of Moses, has authority over the Christian under the terms of the New Covenant. And under this covenant, Christ sets us free from this law or any human law as a yoke over us.
He fulfills what the law pointed to as a good pedagogue “until Christ came” (Gal 3:24). Now that he has come and now that we have the promised Spirit (Gal 3:14), we can serve our Lord Jesus Christ as free men and women.
 Commonplaces 1521, 94.
 “Galatians” 1962: 144.
 “The Distinction between Law and Gospel” 1532, §4.
 “Regard Moses” 1989: 138.
 Ibid., 138.
 Commonplaces 1521, 158.
 Commonplaces 2014: 91.
 “Preface to OT” 1989: 119.
 Inst. 2.7.12.