[The Church] has received the keys of the Kingdom of heaven so that, in her, sins may be forgiven through Christ's blood and the Holy Spirit's action. In this Church, the soul dead through sin comes back to life in order to live with Christ, whose grace has saved us. 526
Catechism number 987
"In the forgiveness of sins, both priests and sacraments are instruments which our Lord Jesus Christ, the only author and liberal giver of salvation, wills to use in order to efface our sins and give us the grace of justification" (Roman Catechism, I, 11, 6).