14 This being so, well may those sinners who have stained the white robe of their sacred baptism fear the just punishments of God. Their remedy is "to wash their robes in the blood of the Lamb"(14)—to restore themselves to their former splendor in the sacrament of Penance—and to school themselves in the practice of Christian virtue. Hence the Apostle Paul's severe warning: "A man making void the law of Moses dies without any mercy on the word of two or three witnesses; how much worse punishments do you think he deserves, who has trodden under foot the Son of God, and has regarded as unclean the blood of the covenant through which he was sanctified, and has insulted the Spirit of grace?... It is a fearful thing to fall into the hands of the living God."(15)
Source: Paenitentiam Agere (Vatican.va)