Catechism of the Catholic Church
True. Para. 1487: The sinner wounds God's honor and love, his own human dignity as a man called to be a son of God, and the spiritual well-being of the Church, of which each Christian ought to be a living stone.
Para. 1440: Sin is before all else an offense against God, a rupture of communion with him. At the same time it damages communion with the Church. For this reason conversion entails both God's forgiveness and reconciliation with the Church, which are expressed and accomplished liturgically by the sacrament of Penance and Reconciliation (Cf. LG 11).