"On the evening of that day, the first day of the week," Jesus showed himself to his apostles. "He breathed on them, and said to them: ‘Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained'" (Jn 20:19, 22-23).
The forgiveness of sins committed after Baptism is conferred by a particular sacrament called the sacrament of conversion, confession, penance, or reconciliation.
The sinner wounds God's honor and love, his own human dignity as a man called to be a son of God, and the spiritual well-being of the Church, of which each Christian ought to be a living stone.
To the eyes of faith no evil is graver than sin and nothing has worse consequences for sinners themselves, for the Church, and for the whole world.
To return to communion with God after having lost it through sin is a process born of the grace of God who is rich in mercy and solicitous for the salvation of men. One must ask for this precious gift for oneself and for others.
The movement of return to God, called conversion and repentance, entails sorrow for and abhorrence of sins committed, and the firm purpose of sinning no more in the future. Conversion touches the past and the future and is nourished by hope in God's mercy.
The sacrament of Penance is a whole consisting in three actions of the penitent and the priest's absolution. The penitent's acts are repentance, confession or disclosure of sins to the priest, and the intention to make reparation and do works of reparation.
Repentance (also called contrition) must be inspired by motives that arise from faith. If repentance arises from love of charity for God, it is called "perfect" contrition; if it is founded on other motives, it is called "imperfect."
One who desires to obtain reconciliation with God and with the Church, must confess to a priest all the unconfessed grave sins he remembers after having carefully examined his conscience. The confession of venial faults, without being necessary in itself, is nevertheless strongly recommended by the Church.
The confessor proposes the performance of certain acts of "satisfaction" or "penance" to be performed by the penitent in order to repair the harm caused by sin and to re-establish habits befitting a disciple of Christ.
Only priests who have received the faculty of absolving from the authority of the Church can forgive sins in the name of Christ.
The spiritual effects of the sacrament of Penance are:
reconciliation with God by which the penitent recovers grace;
reconciliation with the Church;
remission of the eternal punishment incurred by mortal sins;
remission, at least in part, of temporal punishments resulting from sin;
peace and serenity of conscience, and spiritual consolation;
an increase of spiritual strength for the Christian battle.
Individual and integral confession of grave sins followed by absolution remains the only ordinary means of reconciliation with God and with the Church.
Information taken from the Catechism of the Catholic Church Paragraphs 1485-1497
So Why Confess to a Priest? I still don't get it....
What if I answered, because Jesus said so? Would you believe me.
Follow me through this little scriptural journey and you will get it, I promise. (Read for 2 minutes and it will solidify why confession to a priest was established by Jesus Himself).
The power of Christ to forgive sins belongs to Him as God, but he exercised it as a “man.” The Scribes and Pharisees were shocked when Christ pardoned the sins of the paralyzed man. They exclaimed: “Who is this man talking blasphemy? Who can forgive sins but God alone?”(Lk. 5:21).
They were right in that only God can forgive sins. They were wrong, however, because they did not recognize Jesus as God. They did not realize he actually could forgive sins since He was God. For this reason Christ’s response was: “But to prove to you that the Son of Man has authority on earth to forgive sins, he said to the paralyzed man, ‘I order you: get up, and pick up your stretcher and go home’” (Lk. 5:24).
Christ not only manifests his divine power by forgiving the paralytic’s sins, but by curing him of his paralysis. Whenever in the Gospels Christ cured someone of a physical malady, it was always a sign pointing to the spiritual cure of souls He would make available by means of his sacrificial death on the Cross.
Before Christ ascended into heaven He shared his power of forgiving sins with his Apostles. Because Christ is God He can share his powers with whomever he pleases and in whatever way He desires.
On the day of his Resurrection He conferred on the Apostles the power to forgive sins. The words Christ used were: “Receive the Holy Spirit. For those whose sins you forgive, they are forgiven; for those whose sins you retain, they are retained” (Jn 20:23).
Just as Christ gave the Apostles the power to change bread and wine into his Body and Blood at the Last Supper, when He said: “Do this as a memorial of me” (Lk. 22:19), so now, by his words in Jn. 20:23, he gives them another power, that of forgiving sins in the name of God.
The Apostles, in turn, would pass on both of these powers, as well as others, to the men they would eventually ordain bishops and priests. The bishops, who are the successors of the Apostles and who possess the fullness of Christ’s priesthood, would ordain other bishops and priests and thus pass on to them these special powers.
Let us be clear. In Jn. 20:23, the word “retain” gives the Apostles and their successors, the bishops and priests, the right to refuse forgiveness to a person because, in the judgment of the priest, the person does not have real sorrow or firm purpose of amendment. In such a case, forgiveness would have to be “retained” or withheld until the person had the disposition to receive forgiveness.
How would the Apostles know whose sins to forgive or retain, unless they knew what these were, which implies a confession of some sort.
If all Christ wanted his Apostles to do was to proclaim that he had forgiven sins and that all people had to do was to indicate their sorrow to be forgiven, why, then, did he distinguish between forgiving and retaining?
He could have just said: “Go out to the whole world; proclaim the Good News to all creation. He who believes and is baptized will be saved; he who does not believe will be condemned” (Mk. 16:15-16).
This text tells us we must believe and be baptized to attain eternal salvation.
But Jn. 20:23 has Christ saying something different. He really gives the Apostles the power to forgive or retain sins.
There is a big difference between Christ telling the Apostles to preach the availability of forgiveness and actually giving them the power to forgive sins in his name.
(I would like to quote the source of the above information, it was not written by me, but I lost the source information. If you know the source, please e-mail me so I can give credit, where credit is due.)