It is proper to a habit to incline a power to act, and this belongs to a habit, in so far as it makes whatever is suitable to it, to seem good, and whatever is unsuitable, to seem evil. For as the taste judges of savors according to its disposition, even so does the human mind judge of things to be done, according to its habitual disposition. Hence the Philosopher says (Ethic. iii, 5) that "such as a man is, so does the end appear to him." Accordingly charity is inseparable from its possessor, where that which pertains to charity cannot appear otherwise than good, and that is in heaven, where God is seen in His Essence, which is the very essence of goodness. Therefore the charity of heaven cannot be lost, whereas the charity of the way can, because in this state God is not seen in His Essence, which is the essence of goodness.
Reply Obj. 1: The passage quoted speaks from the point of view of the power of the Holy Ghost, by Whose safeguarding, those whom He wills to move are rendered immune from sin, as much as He wills.
Reply Obj. 2: The charity which can fail by reason of itself is no true charity; for this would be the case, were its love given only for a time, and afterwards were to cease, which would be inconsistent with true love. If, however, charity be lost through the changeableness of the subject, and against the purpose of charity included in its act, this is not contrary to true charity.
Reply Obj. 3: The love of God ever works great things in its purpose, which is essential to charity; but it does not always work great things in its act, on account of the condition of its subject.
Reply Obj. 4: Charity by reason of its act excludes every motive for sinning. But it happens sometimes that charity is not acting actually, and then it is possible for a motive to intervene for sinning, and if we consent to this motive, we lose charity. _______________________
TWELFTH ARTICLE [II-II, Q. 24, Art. 12]
Whether Charity Is Lost Through One Mortal Sin?
Objection 1: It would seem that charity is not lost through one mortal sin. For Origen says (Peri Archon i): "When a man who has mounted to the stage of perfection, is satiated, I do not think that he will become empty or fall away suddenly; but he must needs do so gradually and by little and little." But man falls away by losing charity. Therefore charity is not lost through only one mortal sin.
Obj. 2: Further, Pope Leo in a sermon on the Passion (lx) addresses Peter thus: "Our Lord saw in thee not a conquered faith, not an averted love, but constancy shaken. Tears abounded where love never failed, and the words uttered in trepidation were washed away by the fount of charity." From this Bernard [*William of St. Thierry, De Nat. et Dig. Amoris. vi.] drew his assertion that "charity in Peter was not quenched, but cooled." But Peter sinned mortally in denying Christ. Therefore charity is not lost through one mortal sin.
Obj. 3: Further, charity is stronger than an acquired virtue. Now a habit of acquired virtue is not destroyed by one contrary sinful act. Much less, therefore, is charity destroyed by one contrary mortal sin.