This question comes up frequently in the Rite of Christian Initiation of Adults (RCIA) . The RCIA is the usual process for those who wish to become Catholic. The Sacrament of Penance and Reconciliation (AKA Confession) is difficult for many non Catholics to understand. It is the one that they are afraid of receiving for the first time.
The most common question is “Why can’t I just go directly to God? Well in the Sacraments we are going directly to God. All Sacraments are actions of Christ. It is Christ who acts through the Priest.
First it is important to understand that all revelation comes to the Church through Jesus Christ. Christ is the one true source. But there are two ways that God reveals himself: through Scripture and Holy Tradition. Tradition is what has been taught, orally and in writing, by the Apostles and their successors, the bishops. The interpretation of revelation has been entrusted to the Magisterium which is the teaching office of the Church.
Matthew 16:18-19 And so I say to you, you are Peter, and upon this rock I will build my church and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of heaven. Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven.”
John 20:22-23 And when he had said this, he breathed on them and said to them, “Receive the holy Spirit. Whose sins you forgive are forgiven them, and whose sins you retain are retained.”
From Holy Tradition
Fathers of the Church
“Priests have received a power which God has given neither to angels nor to archangels. It was said to them: ‘Whatsoever you shall bind on earth shall be bound in heaven; and whatsoever you shall loose, shall be loosed.’ Temporal rulers have indeed the power of binding; but they can only bind the body. Priests, in contrast, can bind with a bond which pertains to the soul itself and transcends the very heavens. Did [God] not give them all the powers of heaven? ‘Whose sins you shall forgive,’ he says, ‘they are forgiven them; whose sins you shall retain, they are retained.’ What greater power is there than this? The Father has given all judgment to the Son. And now I see the Son placing all this power in the hands of men [Matt. 10:40; John 20:21–23]. They are raised to this dignity as if they were already gathered up to heaven” ( The Priesthood 3:5 [A.D. 387]).
More Fathers of the Church here http://www.catholic.com/library/Confession.asp
The Catechism of the Catholic Church (CCC)
1446 Christ instituted the sacrament of Penance for all sinful members of his Church: above all for those who, since Baptism, have fallen into grave sin, and have thus lost their baptismal grace and wounded ecclesial communion. It is to them that the sacrament of Penance offers a new possibility to convert and to recover the grace of justification. The Fathers of the Church present this sacrament as “the second plank [of salvation] after the shipwreck which is the loss of grace.”
The Power of Sacraments
Sacraments are real actual encounters with God through Jesus and the actions of the Holy Spirit. We say that they are out ward signs that point to an invisible reality. This means that water, bread, wine, oil, for example, that are used in the Sacraments show us that God is actually touching us. We really receive God. They are visible external signs of what God is doing to us in our souls. Sacraments are the most real things that we participate in. Through the Sacraments we are given the most real gift that we can receive.
So Sacraments are not magic spells, or mere rituals, or nice blessings. They are where we meet God. Really. Heaven and earth touch. God uses material things water, wine, bread, oil to be with us. We are embodied souls. So he touches us in a physical way. The incarnation– God becoming man to reveal himself to us is at the heart of the Sacraments..
This is all really nice you might be thinking.
But why does the Catholic Church think that this Sacrament is necessary?
The Sacrament has several Names. It is called the sacrament of:
Conversion: It makes the call to conversion and transformation a real encounter with Christ. It is Jesus who forgives us. It is Jesus who heals us. It is Jesus who gives us grace and hope.
Penance because we are called to make amends for our sins and to transform our lives. This involves a conversion of the heart. If all we do is outward Penance it is a sterile penance—a false penance. When our hearts become hardened by sin, we ask God for a new heart. We ask God for a heart of love. All sin is a failure to love.
Confession because we freely admit that we have sinned. We have turned away from God. Confession to a Priest is essential to this Sacrament. He acts in the person of Christ. When we go to confess our sins, we realize the great mercy of God.
Forgiveness, through the actions of Christ in the person of the Priest we have the peace and joy that God has forgiven us.
Reconciliation. We know that no matter how grave our sin, that God has taken us back. We can once again be in union with the holy Trinity and the whole body of Christ. We also receive the grace to resist sin.
We come to Christ, in the person of a priest, to ask for forgiveness, pardon, and mercy for turning away from Christ. We come to be reconciled with Him and his Church. When we sin we cause harm to the whole Body of Christ.
But we also come to receive the grace and strength to stop sinning and to transform our lives so that we can become holy.
God is the source of this process of Conversion. God never tires. His Love never ends. He is constantly calling us back to him. He waits for us. He changes our hearts. We fall to our knees. We hear the call to confess our sins and turn back to God. When we come face to face with God’s Word, we become aware of our deficiencies and true needs.
We feel—deep within us—the need to become different, to act better, to become holy. We learn to walk in the light of the Lord.
This process of conversion is a real encounter with God. It becomes real through the Sacrament of Reconciliation and Penance. The words that we speak to the confessor is most of all a prayer, because they are addressed to God.
In confession we are given the grace to hate what God hates and to turn away from what displeases God. St. Augustine said sinners have spoiled God’s image in themselves:
Having become unlike God, you look at yourself and you don’t like yourself; you begin then to become like him because what displeases God displease you.
And so we repent and we hear God’s call to conversion and transformation.
St. Augustine also said that Confession is a prayer of Praise—or it is not a sacramental act. We proclaim the great love and mercy of God.
The Words of Absolution say it all:
God, the Father of mercies,
through the death and the resurrection of his Son has reconciled the world to himself
and sent the Holy Spirit among us
for the forgiveness of sins;
through the ministry of the Church
may God give you pardon and peace,
and I absolve you from your sins
in the name of the Father, and of the Son and of the Holy Spirit.
A little Catholic humor. This is just for fun. This could never ever happen.