26 Thus much will suffice to have treated on behalf of true Continence against the Manichees deceitfully continent, lest the fruitful and glorious labor of Continence, when it restrains and curbs the lowest part of us, that is, the body, from immoderate and unlawful pleasures, be believed not healthfully to chasten, but hostilely to persecute. Forsooth the body is indeed different from the nature of the soul, yet is it not alien from the nature of man: for the soul is not made up of body, but yet man is made up of soul and body: and assuredly, whom God frees, He frees the whole man.
Whence our Saviour Himself also took upon Him the whole man, having deigned to free in us all that He made. They who hold contrary to this truth, what does it profit them to restrain lusts? If, that is, they restrain any. What in them can be made clean through Continence, whose such Continence is unclean? And which ought not to be called Continence. Forsooth to hold what they hold is the poison of the devil; but Continence is the gift of God. But as not every one who suffers any thing, or with the greatest endurance suffers any pain whatever, possesses that virtue, which in like manner is the gift of God, and is called Patience; for many endure many torments, in order not to betray either such as are wickedly privy with them in their crimes, or themselves; many in order to satiate glowing lusts, and to obtain, or not to abandon those things, whereunto they are bound by chain of evil love; many on behalf of different and destructive errors, whereby they are strongly held: of all of whom far be it from us to say that they have true patience: thus not every one, who contains in any thing, or who marvellously retrains even the very lusts of the flesh, or mind, is to be said to possess that continence, of the profit and beauty of which we are treating. For certain, what may seem marvellous to say, through incontinence contain themselves: as if a woman were to contain herself from her husband, because she has sworn this to an adulterer. Certain through injustice, as if spouse yield not to spouse the due of sexual intercourse, because he or she is already able to overcome such appetite of the body. Also certain contain deceived by false faith, and hoping what is vain, and following after what is vain: among whom are all heretics, and whosoever under the name of religion are deceived by any error: whose continence would be true, if their faith also were true: but, whereas that is not to be called faith, on this account, because it is false; without doubt that also is unworthy the name of continence. For what? Are we prepared to call continence, which we must truly say is the gift of God, sin? Far be from our hearts so hateful madness. But the blessed Apostle says “Every thing that is not of faith is sin.” What therefore has not faith, is not to be called continence.
Source: On Continence (New Advent)