How can the pastor forgive sins?

In private confession and absolution, and each Sunday in corporate worship, sinners confess their sins to the Lord God and look to Christ Jesus and His cross in faith for the forgiveness of sins; and, the pastor announces unto them the grace of God and, in the stead and by the command of our Lord Jesus Christ, forgives the sins of penitent sinners. “But who can forgive sins but God alone?” some may ask.