My God, I am sorry for my sins with all my heart. In choosing to do wrong and failing to do good, I have sinned against you whom I should love above all things. I firmly intend, with your help, to do penance, to sin no more, and to avoid whatever leads me to sin. Our Savior Jesus Christ suffered and died for us. In his name, my God, have mercy. Amen. 

"Those who approach the sacrament of Penance obtain pardon from God's mercy for the offense committed against him, and are, at the same time, reconciled with the Church which they have wounded by their sins and which by charity, by example, and by prayer labors for their conversion." CCC 1422

If the Church is to fulfill in its entirely her task of saving mankind she needs the power to forgive sins. It is a power essentially different from her mission to preach the Gospel and baptize. In baptism, indeed all sins and the punishment due to them are remitted. Baptism is the first justification. But the first justification is also the first entry into the realm of the supernatural which works entirely by God's grace and which asks of the person baptized no more than that he turn away from sin and turn in faith to Christ.

Penance is something different. A baptized person who sins again, sins against God to whom, since his baptism in the name of the Most Holy Trinity, he belongs. He also betrays the Church of which he is now a member. Thus, the new atonement assumes the character of a legal trial, with accusation, sentence and satisfaction.

The practice of penance has varied considerably down the centuries. In very early days satisfaction, usually in the form of public penance, was very much to the fore. Re-acceptance into the Church community normally took place only after completion of the penance imposed. More and more, however, penance has withdrawn from the public domain and today only the private administration of the sacrament is still in use.

The development of the system of confession shows that misunderstanding easily arises above the nature of penance. In the face of all attacks - by Wycliffe, the Reformers, liberal dogmatic historians and modernists - the Church has always maintained the judicial character of the sacrament of penance and drawn the necessary conclusion.

THE CHURCH TEACHES

The Church has the power to forgive all sins. This forgiveness of sins is a true sacrament instituted by Christ, different from Baptism, particularly on account of its judicial form. Sins are forgiven only by the sacrament of penance. Sins are forgiven by absolution which can only be given by an authorized priest. It is a real judicial pardon. The Church has the power to reserve certain cases.

On the part of the sinner contrition, confession and satisfaction are required.
 

1. Contrition is aversion to the sins committed.
2. Perfect contrition remits sin even before confession if it is joined with the intention to confess.
3. Imperfect contrition (attrition) is sufficient if there is confession, and is a good and salutary thing. Reconciliation must cover all mortal sins committed since Baptism and not previously confessed.
4. Satisfaction is the effect of the sacrament is reconciliation with God, that is, the remission of sins and the eternal punishment but not all the temporal punishment.