In Catholicism, the Sacrament of Reconciliation is a sacrament instituted by Christ to forgive sins that a person commits after baptism. It’s more commonly called ‘Confession’. A penitent carefully examines his conscience to determine what sins he’s committed since his last confession, arouses true sorrow for having sinned, & confesses the sins (their nature & number) to the priest. If the penitent ‘hides’ a sin from the priest, it is not forgiven. Only mortal sins must be absolved through Confession. Although venial sins can be forgiven by a priest during this sacrament, the Church teaches that they don’t have to be confessed in order to be forgiven.