On what doctrine is the Lutheran practice of Absolution based? It is based on the following facts that we teach:
1. Christ, the Son of God, took upon Himself every sin of every sinner, counting them as His own. Accordingly, John the Baptist points to Christ and says, “Behold, the Lamb of God, who takes away the sin of the world!” (John 1:29)
2. By leading His life in abject poverty, by His suffering, crucifixion, and death, Christ wiped out the record of the world’s sin and gained for us remission of all sins. No person living — from Adam to the last human yet to be born — is excused from this plan. For Paul writes in 2 Corinthians 5:21 “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.” Isaiah states in 53:5 “But he was wounded for our transgressions; he was crushed for our iniquities; upon him was the chastisement that brought us peace, and with his wounds we are healed.” And even in the Old Testament prophecy written earlier that Isaiah, we hear the Messiah wail: “I am forced to pay back what I did not steal” (Ps 69:5).
3. By raising His Son, Jesus Christ, from the dead, God the Father confirmed and put His stamp of approval on the work of reconciliation and redemption that Christ had finished on the cross, ‘It is finished,’ so I announce, ‘It is finished indeed!’ You sinners are redeemed. Forgiveness of sins is prepared for everybody. It is already here. It must not first be acquired by you.
4. In addition to Christ commanding that the Gospel be preached to every creature, He at the same time commanded that forgiveness of sins should be preached to all people. This is what we call the Good News: “All that is necessary for your salvation has been accomplished. When you ask, ‘What must we do to be saved?’ please remember that all has been done. There is nothing more to do. All you have to do is believe that everything has been done for you — and you will be saved.”
5. Christ issued a general command to His apostles and their successors in office to preach the Gospel, that is, the forgiveness of sins. Yet He also commanded us to minister to each individual who desires forgiveness by offering this comfort: “You are reconciled to God.” For if forgiveness of sin has been acquired for all, it has also be acquired for each individual. If I can offer it to all, I can offer it to each individual. Not only am I allowed to do this, I am ordered to do it. If I fail to do it, I am a servant of Moses and not a servant of Christ.
6. Now that forgiveness of sin has been acquired as stated, not only does a pastor have a special commission to proclaim it, but also every Christian — male or female, adult or child — is commissioned to do this. Even a child’s Absolution is just as certain as the Absolution of St. Peter — yes, even as the Absolution of Christ would be, were He again to stand visibly before people and say, “Your sins are forgiven.” There is no difference, because, note well, it is not a question of what humans must do but what has been done by Christ.
Law & Gospel: How to Read and Apply the Bible by C. F. W. Walther (A Reader’s Edition)