The soul needs only one thing: the word of God. When this is missing, the soul lacks the one item that is essential. Having the word of God makes the soul rich—for what else could it possibly need? The word of God brings life, truth, light, peace, righteousness, salvation, joy, liberty, wisdom, power, grace, glory, and every other blessing imaginable. This is why in Psalm 119 and in many other places in the Bible there is a yearning and sighing for the word of God. This also makes clear why there is no greater disaster than when God’s wrath results in a famine when his word is not heard (for example, see Amos 8:11). Similarly, there is no greater mercy than when God sends his word as in Psalm 107:20: “He sent out his word and healed them, and delivered them from destruction.” Thus Christ was given to the world for no other ministry than the word. Similarly, all the apostles, bishops, and priests have been called and instituted only for the ministry of the word.
You may ask, “What is the word of God and how should it be used since there are so many words of God?” I respond by quoting what Paul says in Romans 1. The word is the gospel of God concerning his son, who was made flesh, suffered, rose from the dead, and was glorified through the Spirit who makes us holy. To preach Christ means to feed the soul, make it righteous, set it free, and save it, provided the preaching is believed. For faith alone is the saving and efficacious use of the word of God. The apostle Paul in Romans 10:9 writes: “If you confess with your lips that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.” Paul also says in Romans 10:4: “For Christ is the end of the law so that there may be righteousness for everyone who believes.” Also, in Romans 1:17 p 54 it states: “The one who is righteous shall live by faith.” The word of God cannot be received or honored by any works but must be grasped by faith alone. Therefore, it is clear that the soul needs only the word of God for life and righteousness; it is justified by faith alone and not by any works. If the soul were able to be justified by any other means it would not need the word of God, and then it also would not need faith. It should be underlined that this faith cannot exist in connection with works. In other words, if you hold this faith and at the same time claim to be justified by works, whatever their character, you are missing the point. This would be like “limping with two different opinions” (1 Kings 18:21), or it would be like worshiping Baal and kissing one’s own hand (Job 31:27–28), which, as Job says, is a great iniquity. Therefore, when you begin to trust, you discover at the same time that all things in you are wholly blameworthy, sinful, and deserving of condemnation, as Paul says in Romans 3:23: “All have sinned and fall short of the glory of God.” He also p 55 states in Romans 3:10–12: “There is no one who is righteous, not even one … all have turned aside, together they have become worthless.” When you grasp this, you will know the necessity of Christ, who suffered and rose again for you. Believing in him, you become a new person—one whose sins are forgiven and one who is justified by the merits of another, namely Christ alone.
It is only possible for this faith to rule in the inner person as Paul says in Romans 10:10: “For one believes with the heart and so is justified.” Since we are justified by faith alone, it is clear that the inner person cannot be justified, freed, or saved by any external work or act, and such works, whatever they may be, have nothing to do with the inner person. Therefore, only ungodliness and unbelief of the heart make a person a condemned servant of sin—this cannot be caused by any external work or act of sin. It follows that it ought to be the primary goal of every Christian to put aside confidence in works and grow stronger in the belief that we are saved by faith alone. Through this faith the Christian should increase in knowledge not of works but of Christ Jesus and the benefits of his death and resurrection. This is what Peter teaches in the fifth chapter of his first letter (1 Pet. 5:10). No other work makes a Christian. Thus, when the Jews asked Christ in John 6:28 what they must do to perform the works of God, he dismissed their multitude of activities and pointed to one work, saying “This is the work of God, that you believe in him whom he has sent” (John 6:29), for “it is on him that God the Father has set his seal” (John 6:27).
Hans Baldung Grier, Martin Luther with a Nimbus and Dove, 1521, woodcut.
Therefore, true faith in Christ is an incomparable treasure that brings a person complete salvation and deliverance from all evil, as Jesus says in Mark 16:16: “The one who believes and is baptized will be saved, but the one who does not believe will be condemned.” The prophet Isaiah contemplated this treasure p 56 and foretold it: “The Lord will make a small and consuming word upon the land and it will overflow with righteousness” (Isa. 10:22). It is as if Isaiah said, “Faith, which is a small but perfect fulfillment of the law, will fill believers with such complete p 57 righteousness that they will need nothing else to be righteous.” Or as Paul says in Romans 10:10: “For one believes with the heart and so is justified.”
Martin Luther, The Freedom of a Christian, trans. Mark D. Tranvik (Minneapolis, MN: Fortress Press, 2008), 53–57.