The two most common symbols of the Sacrament of Reconciliation are the keys of St. Peter and the purple stole worn by the priest. Also known as confession or going to confession, the Sacrament of Reconciliation is the normal means by which Catholics are forgiven for post-baptismal sins.
The symbol of the keys originates in chapter 16 of the Gospel of Matthew. Catholic belief holds that in verses 18 and 19 Christ tells Peter that he is the rock upon which the Church is to be built and that he is giving him the keys to the kingdom of heaven where whatever he binds and looses on earth is also bound and loosed in heaven. Catholics also cite John 20:21-23, where Jesus tells the Apostles that whatever sins they forgive on earth are forgiven in heaven, as a Scriptural basis for the sacrament.
The stole is a symbol of the ordained priesthood. The Church teaches that whenever a priest celebrates the sacraments he is acting in the person of Christ. The color purple symbolizes sorrow and repentance, and is always worn by the priest during the penitential seasons of Lent and Advent. For a confession to be valid in the eyes of the Church, the penitent must feel true contrition for his sins and the priest must use the words, "I absolve you of your sins."