Why do we confess to a Priest?
After his resurrection, Jesus passed on his mission to forgive sins to his ministers, telling them: “As the Father has sent me, even so I send you . . . Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained” (John 20:21)
If God sent his son to forgive us our sins why is it so unreasonable to think Jesus gave his authority to others to forgive our sins? In the early Church, sins where often confessed in public and often in private, but was never limited to silence with God alone.
So in other words, we confess to a priest, not because he himself has the power to forgive sins, but because he acts as an agent, in the name of God, and forgives sins in His name.
The fact that the priest is a sinner, as are all men, does not affect the power which he exercises. The power comes to him from his office. The same is true with a President or with a judge in our civil courts. The private lives of these individuals does not affect the authority which they have under the Constitution to act.