"Then he breathed on them and said: ‘Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; If you retain the sins of any, they are retained'" (John 20:22-23). By speaking these words, Jesus gave the Apostles the power and authority to forgive sins in the name of God. This power to forgive sins is passed on through Holy Orders to all priests. All validly ordained priests can forgive sins with the power given them by God. It is not the priests that do the forgiving, but it is God who does the forgiving, through the hands and words of the priests (CCC 1441). As St. Paul says: "All this has been done by God, who has reconciled us to himself through Christ and has given us the ministry of reconciliation (2 Cor. 5:18).
The sacrament of reconciliation may also be called "confession." But there is a proper way to celebrate this sacrament, so that it will be a valid confession and the penitent's sins will be forgiven.
First of all, one must make an examination of conscience. This is done by attempting to call to mind all sins committed since one's last good confession. The usual procedure is to follow the ten commandments and try to recall, as best as one can, all violations committed against those commandments.
But it is not enough to just confess our sins. We must be sorry that we committed those sins. Our sorrow is sufficient when we express supernatural contrition. Our sorrow is supernatural when it has God as its object. Supernatural contrition can be perfect, when it arises from a love of God. Such sorrow comes from having offended God (CCC 1452). Supernatural contrition is imperfect when it arises from a fear of God. Such sorrow comes from the fear of God's punishments, especially hell and the loss of heaven (CCC 1453). Sorrow is also imperfect when we find our sins hateful in themselves. Natural contrition, sorrow that arises out of the fear of negative repercussions from others or from the situation, is not sufficient for forgiveness. We must be sorry for all of our mortal sins, and for at least one venial sin if we do not have any mortal sins, but only venial sins, to confess. Our sorrow must also be interior–it must come from the heart, and not just from the lips. We must be sorry, even though we cannot always feel it. Besides having sorrow, we must also have a firm purpose of amendment, which means we must intend, with the help of God's grace, never to commit these sins again. We must have the attitude that if God gave us all the grace we needed to never commit those sins again, we would be resolved never to commit them again. Our purpose of amendment should also be specific, meaning we should have a plan as to how we are going to keep from committing these sins again. Before going to confession, we should pray an act of contrition: "O my God, I am heartily sorry for having offended You, and I detest all my sins, because of Your just punishments, but [also] or [most of all] because they offend You, my God, Who art all-good and deserving of all my love. I firmly resolve, with the help of Your grace, to do penance, sin no more, and amend my life;" or "O my God, I am sorry for my sins with all my heart. In choosing to do wrong and in failing to do good, I have offended you, Whom I should love above all things. I firmly intend, with the help of Your grace, to do penance, sin no more, and avoid the occasions of sin. Our Savior Jesus Christ suffered and died for us. In His name, have mercy."
Once we have made a sincere act of contrition, we are ready to confess to the priest. When we enter the confessional or reconciliation room, the priest reads a passage from the Scriptures, and then asks the penitent to make his confession. In our confession, we must state all mortal sins we have committed since our last good confession, and our venial sins if we so choose (CCC 1456, 1458). Along with confessing the sins we have committed, we must also state the number of times we committed each sin, or the approximate number if we cannot remember the exact number of times we have committed them. We must mention any circumstances which change the nature of the sin, and must not omit anything because of shame or for other reasons. If, however, we sincerely forget to confess a mortal sin, we must still confess that sin when we next confess. If, however, we knowingly conceal a mortal sin from our confessor, we commit the sin of sacrilege for mistreatment of the sacrament of reconciliation (CCC 1456). Once we have confessed, the priest is bound by the seal of confession never to reveal what has been said during the confession, and may never use information learned in the confession to the detriment of the penitent.
Before the words of absolution, the priest gives a penance, according to the gravity of the penitent's sins, in order that he makes atonement for the sins he has committed, since we must suffer temporal punishment even for sins that have been forgiven (CCC 1459).
After the priest has assigned a penance, he will say the words of absolution, which conclude, "I absolve you from your sins in the name of the Father, and of the Son, and of the Holy Spirit" (CCC 1449). After this, the penitent is told to "go in peace," at which time he leaves and, if possible, immediately does his penance.
Some go to confession frequently, and others not so freqently, but all Christians should confess at least once a month. Through the sacrament of reconciliation, we receive sacramental graces that help us to avoid sin in the future, and we receive good spiritual direction from our confessor. It is also important for us to realize that if we have committed a mortal sin, we must be absolved of that sin through the sacrament of reconciliation before we can receive holy Communion, to avoid the sin of sacrilege in case we are in the state of mortal sin, even if our sins may have been forgiven through an act of perfect contrition (CCC 1457). So we should go to confession each time we commit mortal sin. We must also remember that it is a commandment of the Church that if we are guilty of mortal sin, we must confess at least once every year (CCC 1457).