The Church has given us the sacrament of Reconciliation or Penance, Confession and Conversion that we may be cleansed of all our sins.
This sacrament forgive forgives us all the sins committed by one after his/her baptism. St Francis de Sales says "Never allow yourself to be burdened and become heavy with sin. If the lioness has been in the neighbourhood of other beasts she hastens to away their scent, lest it should be displeasing to her lord. So the soul which has ever so little consented to sin, ought to abhor itself and make haste to seek purification, out of respect to Divine Gaze who beholds it always. Why should we die a spiritual death when there is a sovereign remedy available." This is found in the Sacrament of Reconciliation or Penance and Confession.
Confession not only gives one absolution for mortal and venial sins, but also great strength to help in avoiding sin. The sacrament helps us to see our failings and gives us abundant grace to make up whatever loss one has incurred through those faults. It helps us to exercise the graces of humility, obedience, simplicity and love, and through the act of confession practice more virtue than in any other sacrament.
This sacrament is only between the priest and the penitent (one making confession). The sacrament is conferred in four parts.
CONTRITION: The penitent must be aware of his sinfulness and be humble and contrite or repentant. When he goes to the priest in the confessional he says "Forgive me Father for I have sinned" and then says how long it has been since his last confession.
CONFESSION: Before going to the priest the penitent should do proper examination of his conscience and then tell the priest all his sins, including those he has previously omitted or forgotten. St Francis de Sales says "When confessing one's sins mention the sins actually committed after closely examining one's conscience. By not doing this one does not get the grace that the sacrament gives. Confession is an entirely and strictly very private matter between the priest and the penitent. The priest will never divulge anything said in confession not even in a court of law. St John Nepomucene was killed only because he would not divulge what was told to him in confession. Confession takes place in a small room or a specially designated part of the church in the confessional. Here a screen separates the penitent and the priest which ensures privacy and anonymity. In certain cases if both the priest and the penitent agree, Confession can take place in a separate room as a Dialogue Confession.
ACT OF PENANCE: The priest gives the penitent certain actions to perform as a penance. This may take the form of special prayers or some other fitting action. This helps the penitent to show his sorrow for his sinful acts. It also helps him to overcome his faults and the harm he has caused to others. It also helps the penitent to be reconciled with man, the Church and God and live a life as a disciple of Jesus.
ABSOLUTION: After the penitent accepts the penance given to him by the priest he is absolved or pardoned and forgiven for his sins. This is done by virtue of the authority given by Jesus at Pentecost to the Apostles when He said "Receive the Holy Spirit; for those whose sins you forgive they are forgiven; those sins you retain, they are retained, and later down the ages through the Church to her priests.”
While Absolution is being given, the penitent has to say a meaningful Act of Contrition.
"O my God, I am heartily sorry for having offended Thee through my sins. I detest all my sins because they displease You who art infinitely good and infinitely pure and all deserving of my love. I beg pardon for my sins and firmly resolve with the help of thy grace to sin no more and to avoid the occasions of sin."