The Lord himself taught us to pray: "Forgive trespasses..." (Luke 11:4).   This links our forgiveness to one another's offenses to the forgiveness of our sins that God will grant us.

      Human nature is frail and weak.   Until our dying day is over we do not want to be without recourse to God's infinite mercy.

      It is honest of us to confess our sins.   First of all we should tell God that we need His mercy.   We own up to sin before God.

      Catholics are taught to confess sins to a priest because the priest has authority to forgive sin in the name of Jesus.   That is one of the works which a priest is ordained to do.   This is fulfilling the ministry of the Good Shepherd who seeks the lost sheep.