This is a trustworthy saying. It means that our Old Adam with his evil deeds and desires should be drowned by daily contrition and repentance, and die, and that day by day a new man should arise, as from the dead, to live in the presence of God in righteousness and purity now and forever. The use of the Keys is that special power and right which Christ gave to his church on earth, to forgive the sins of the penitent sinners, but to refuse forgiveness to the impenitent as long as they do not repent. A Christian congregation with its called pastor uses the Keys in accordance with Christ's command by forgiving those who repent of their sin and are willing to amend, and by excluding from the congregation those who are plainly impenitent that they may repent. I believe that, when this is done, it is as valid and certain in heaven also, as if Christ, our dear Lord, dealt with us himself.
Confession has two parts.
Before God we should plead guilty of all sins, even those we are not aware of, as we do in the Lord's Prayer. But before the pastor we should confess only those sins which we know and feel in our hearts. Consider your place in life according to the Ten Commandments. It is the true body and blood of our Lord Jesus Christ together with the bread and wine, instituted by Christ for us Christians to eat and to drink. This cup is the new covenant in my blood, which is poured out for you for the forgiveness of sins.