1453 The contrition called “imperfect” (or “attrition”) is also a gift of God, a prompting of the Holy Spirit. It is born of the consideration of sin’s ugliness or the fear of eternal damnation and the other penalties threatening the sinner (contrition of fear). Such a stirring of conscience can initiate an interior process which, under the prompting of grace, will be brought to completion by sacramental absolution. By itself however, imperfect contrition cannot obtain the forgiveness of grave sins, but it disposes one to obtain forgiveness in the sacrament of Penance.52
1471 The doctrine and practice of indulgences in the Church are closely linked to the effects of the sacrament of Penance. What is an indulgence? An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints. 81 “An indulgence is partial or plenary according as it removes either part or all of the temporal punishment due to sin.” 82 The faithful can gain indulgences for themselves or apply them to the dead. 83
1411 Only validly ordained priests can preside at the Eucharist and consecrate the bread and the wine so that they become the Body and Blood of the Lord.
1416 Communion with the Body and Blood of Christ increases the communicant’s union with the Lord, forgives his venial sins, and preserves him from grave sins. Since receiving this sacrament strengthens the bonds of charity between the communicant and Christ, it also reinforces the unity of the Church as the Mystical Body of Christ.