Actus Contritionis - Act of Contrition
This is the official version of the Act of Contrition that corresponds perfectly with all the necessary elements for contrition as infallibly defined in the Council of Trent: “sorrow of soul, and a hatred of sin committed, with a firm purpose of not sinning in the future.” This prayer in a unique way is able to instill in the heart all these necessary sentiments for true contrition including both an act of imperfect contrition, sorrow for sin derived from fear of punishment, as well as perfect contrition, sorrow for offending God.
Before making an act of contrition, especially before the sacrament of confession, it is first necessary to make a good examination of conscience. (Here is one of the most thorough examination of consciences for adults one can find, which also has an imprimitur.) After an examination of conscience, one of the most important elements consists in stirring up a sincere and total hatred and detestation of all sins committed. The more hatred for sins, the more effective the act of contrition will be. It is important to note that there is no real sin that can be forgiven without contrition, as per the words of Christ, “Except you repent…” (Luke 13:5). This prayer is typically prayed at night before bed as well as during the sacrament of Confession. (More About Contrition Here)
Deus meus, ex toto corde poenitet me omnium meorum peccatorum, eaque detestor, quia peccando, non solum poenas a Te iuste statutas promeritus sum, sed praesertim quia offendi Te, summum bonum, ac dignum qui super omnia diligaris. Ideo firmiter propono, adiuvante gratia Tua, de cetero me non peccaturum peccandique occasiones proximas fugiturum. Amen.
Oh my God, from all my heart I am sorry for all my sins, and I detest them, not only because in sinning, I deserve the penalties that you have justly established, but especially because I have offended Thee, who art the greatest good, and worthy beyond all my love. Therefore I firmly purpose, with the help of Thy grace, from henceforth to sin no more and flee the next occasions of sinning. Amen.
Confiteor - I Confess
This prayer is used most frequently for confession and during holy Mass. Many eastern liturgies begin with confession made by the priest. The Latin Rite confiteor originated by being said by the priest before Mass and eventually by the 10th or 11th century holy Mass began with this prayer in the prayers of the foot of the altar. This version of the prayer dates back to at least the 8th century. Some variants existed locally until Pius V’s Roman Missal, where all other versions not in existence for more than 200 years were suppressed, leaving in existence the various religious orders’ versions such as the Dominicans who invoke St Dominic in their version. The Confiteor is said by the priest in preparation for Mass and then by the servers and again it is said as a preparation immediately before receiving Holy Communion. This prayer is also said each night during compline after an examination of conscience. Finally, the Confiteor is said during the sacrament of extreme unction. The Confiteor is a very powerful prayer that invokes Saints by name to pray for the penitent to assist in the act of contrition and to receive full absolution from Almighty God.
Confiteor Deo omnipotenti, beatae Mariae semper Virgini, beato Michaeli Archangelo, beato Joanni Baptistae, sanctis Apostolis Petro et Paulo, omnibus Sanctis, et vobis, fratres (et tibi pater), quia peccavi nimis cogitatione, verbo et opere: mea culpa, [strike breast] mea culpa, [strike breast] mea maxima culpa [strike breast]. Ideo precor beatam Mariam semper Virginem, beatum Michaelem Archangelum, beatum Joannem Baptistam, sanctos Apostolos Petrum et Paulum, omnes Sanctos, [et vos, fratres (et te, pater)] orare pro me ad Dominum Deum nostrum. Amen.
I confess to almighty God, to blessed Mary ever Virgin, to blessed Michael the archangel, to blessed John the Baptist, to the holy apostles Peter and Paul, to all the saints, and to you my brothers (and to thee, father) that I have sinned exceedingly in thought, word, and deed, through my fault, [strike breast] through my fault, [strike breast] through my most grievous fault [strike breast]. Therefore, I beseech blessed Mary ever Virgin, blessed Michael the archangel, blessed John the Baptist, the holy apostles Peter and Paul, all the saints, [and you my brothers (and thee father)] to pray for me to the Lord our God. Amen.
Misereatur nostri omnipotens Deus, et dimissis peccatis nostris, perducat nos ad vitam aeternam. Amen.
May Almighty God have mercy upon us, forgive us our sins, and bring us unto life everlasting. Amen.
Indulgentiam, absolutionem, et remissionem peccatorum nostrorum, tribuat nobis omnipotens et misericors Dominus. Amen.
May the almighty and merciful Lord grant us pardon, absolution, and remission of our sins. Amen.
A Prayer for Penance and Faith
Indulgence of 300 days
Deus meus, credo in te, spero in te, amo te super omnia ex tota anima mea, ex toto corde meo, ex totis viribus meis: amo te quia es infinite bonus et dignus qui ameris; et quia amo te, me paeitet ex toto corde te offendisse: miserere mihi peccatori. Amen.
My God, I believe in Thee, I hope in Thee, I love Thee above all things with all my soul, with all my heart and with all my stregth; I love Thee because Thou art infinitely good and worthy of being loved; and because I love Thee, I repent with all my heart of having offended Thee; have mercy on me, a sinner. Amen.