The ultimate aim of the keys is the forgiveness of sins. The loosing key, like baptism, creates new life. The keys are efficacious because of their christological character. For Christ has not ordained authorities or powers or lordships in His church, but ministries, . . . Thus, the application of the loosing key is God's act, which delivers the life-giving forgiveness of sins won by Christ.
Assurance stems from the application of the loosing key.
A simple trusting heart can boldly rely on God's action. I have been absolved of my sins, however many and great they may be, by means of the key, on which I may rely. Let no one remind me of my sins any longer. In the 17th century, certain heirs of Luther began to question whether the proclamation of the loosing key had not become too easy and free. They are sure of this because it is of course not possible to be saved on account of one's life, but they believe in Christ and put all their trust in Him, that this cannot fail, and they will surely be saved by such faith.