Catechism:
1458 Without being strictly necessary, confession of everyday faults (venial sins) is nevertheless strongly recommended by the Church.59 Indeed the regular confession of our venial sins helps us form our conscience, fight against evil tendencies, let ourselves be healed by Christ and progress in the life of the Spirit. By receiving more frequently through this sacrament the gift of the Father’s mercy, we are spurred to be merciful as he is merciful:60
Code:
Whoever confesses his sins . . . is already working with God. God indicts your sins; if you also indict them, you are joined with God. Man and sinner are, so to speak, two realities: when you hear "man" - this is what God has made; when you hear "sinner" - this is what man himself has made. Destroy what you have made, so that God may save what he has made. . . . When you begin to abhor what you have made, it is then that your good works are beginning, since you are accusing yourself of your evil works. The beginning of good works is the confession of evil works. You do the truth and come to the light.61
IX. THE EFFECTS OF THIS SACRAMENT
1468 "The whole power of the sacrament of Penance consists in restoring us to God’s grace and joining us with him in an intimate friendship."73 Reconciliation with God is thus the purpose and effect of this sacrament. For those who receive the sacrament of Penance with contrite heart and religious disposition, reconciliation "is usually followed by peace and serenity of conscience with strong spiritual consolation."74 Indeed the sacrament of Reconciliation with God brings about a true “spiritual resurrection,” restoration of the dignity and blessings of the life of the children of God, of which the most precious is friendship with God.75
1469 This sacrament reconciles us with the Church. Sin damages or even breaks fraternal communion. The sacrament of Penance repairs or restores it. In this sense it does not simply heal the one restored to ecclesial communion, but has also a revitalizing effect on the life of the Church which suffered from the sin of one of her members.76 Re-established or strengthened in the communion of saints, the sinner is made stronger by the exchange of spiritual goods among all the living members of the Body of Christ, whether still on pilgrimage or already in the heavenly homeland:77
Code:
It must be recalled that . . . this reconciliation with God leads, as it were, to other reconciliations, which repair the other breaches caused by sin. The forgiven penitent is reconciled with himself in his inmost being, where he regains his innermost truth. He is reconciled with his brethren whom he has in some way offended and wounded. He is reconciled with the Church. He is reconciled with all creation.78
1470 In this sacrament, the sinner, placing himself before the merciful judgment of God, anticipates in a certain way the judgment to which he will be subjected at the end of his earthly life. For it is now, in this life, that we are offered the choice between life and death, and it is only by the road of conversion that we can enter the Kingdom, from which one is excluded by grave sin.79 In converting to Christ through penance and faith, the sinner passes from death to life and "does not come into judgment."80
scborromeo.org/ccc/p2s2c2a4.htm#VII