Martin Luther's Writings

21. This is the authority of which Christ speaks, in Matthew 9[:6–8], to the unbelieving scribes, "That you may know that the son of man has authority on earth to forgive sins—he said to the paralytic—'Arise, take up your bed and go home.' And he rose and went home, When the crowds saw it, they were afraid, and they glorified God, who had given such authority to men." Now this authority to forgive sins is nothing other than what a priest, indeed, if need be, any Christian, may say to another when he sees him afflicted or affrighted in his sins. He can joyously speak this verdict, "Take heart, your sins are forgiven" [Matt. 9:2].

And whoever accepts this and believes it as a word of God, his sins are surely forgiven. Where, however, there is no such faith, it would do no good even if Christ or God himself spoke the verdict. For God cannot give a person something he does not want to have. And that person does not want to have it, who does not believe that it is being given to him; he does the word of God a great dishonor, as was said above. You see, then, that the whole church is full of the forgiveness of sins. But few there are who really accept and receive it. For they do not believe it and would rather rely upon their own works. So it is true that a priest genuinely forgives sin and guilt, although he is in no position to give to the sinner that faith which receives and accepts the forgiveness. For this faith God must give. Nevertheless the forgiveness is genuine, as true as if God had spoken it, whether it is grasped by faith or not. Such authority to forgive sins, and thus to render a verdict in God's place, no one possessed in the Old Testament, neither high priest nor ordinary priests, neither kings nor prophets, nor anyone else among the people. The only exceptions occurred at God's express order, as when Nathan confronted King David [II Sam. 12:1–15]. But in the New Testament every Christian has this authority to forgive sins, where a priest is not at hand. And he has it through the promise of Christ, where he said to Peter, "Whatever you loose on earth shall be loosed in heaven" [Matt. 16:19]. Had this been said to Peter alone, then in Matthew 18[:18] Christ would not have said to all in general, "Whatever you loose on earth shall be loosed in heaven." There he is speaking to all Christendom, and to each [Christian] in particular. The great thing about the Christian is that God cannot be fully loved and praised if we are no longer given to hear more than one man speaking to us in such a word. Now the world is full of Christians, yet no one pays any attention to this or gives God thanks.

To sum it all up:
Whoever believes, to him: everything is helpful, nothing is harmful. Whoever does not believe, to him: everything is harmful, nothing is helpful.