(God) gave himself to us through his Spirit. By the participation of the Spirit, we become communicants in the divine nature.... For this reason, those in whom the Spirit dwells are divinized. 37
Catechism number 1991
Justification is at the same time the acceptance of God's righteousness through faith in Jesus Christ. Righteousness (or "justice") here means the rectitude of divine love. With justification, faith, hope, and charity are poured into our hearts, and obedience to the divine will is granted us.