From Narrative Commentary to the Divine Service by John Pless:
It is only through the forgiveness of sins that we enter into the life of heaven. To confess your sins is to speak the truth about your life. This truth you learn from the Word of God and He, through the Holy Spirit, teaches you to say what He says (same/say). God seeks that truth in the heart and on the lips. To confess your sin is to same/say “Amen” to God’s just verdict that you have sinned against Him and so deserve only death and hell.
The truth of your sinfulness is answered by the truth of God’s forgiveness for the sake of the suffering and death of His Son. From the lips of a man “called and ordained” as a servant of the Word, your ears hear God Himself speaking absolution, that is, the forgiveness of sins. To that forgiveness, faith says “Amen,” to this verdict of God, “Amen” is the great word of worship; it indicates that the gift has been received.