In the February 1994 “Quick Questions” column you stated that when a person commits mortal sin he implicitly rejects God and the entire life of holiness he had led up to that point, including the reward he would have gotten for his good deeds. When he repents and comes back to God through the sacrament of confession, does this mean he will have to start from zero in gaining new rewards?
No. The common teaching of Catholic theologians is that there is a “revival of merit” when a person comes back to God. When a person comes back to God, he implicitly reaffirms the prior life of holiness he had led, so his rewards for that life are restored.
In Infinita Dei Misericordia (1924), Pope Pius XI taught that penitents have “the fullness of the merits and the gifts which they lost through sin . . . restored and given back.” Thomas Aquinas taught the same thing (Summa Theologiae 3a:89:5).