Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 25

Chapter 25.—That We Should Not Endeavor By Sin to Obviate Sin.

But, we are told, there is ground to fear that, when the body is subjected to the enemy’s lust, the insidious pleasure of sense may entice the soul to consent to the sin, and steps must be taken to prevent so disastrous a result.  And is not suicide the proper mode of preventing not only the enemy’s sin, but the sin of the Christian so allured?  Now, in the first place, the soul which is led by God and His wisdom, rather than by bodily concupiscence, will certainly never consent to the desire aroused in its own flesh by another’s lust.  And, at all events, if it be true, as the truth plainly declares, that suicide is a detestable and damnable wickedness, who is such a fool as to say, Let us sin now, that we may obviate a possible future sin; let us now commit murder, lest we perhaps afterwards should commit adultery?  If we are so controlled by iniquity that innocence is out of the question, and we can at best but make a choice of sins, is not a future and uncertain adultery preferable to a present and certain murder?  Is it not better to commit a wickedness which penitence may heal, than a crime which leaves no place for healing contrition?  I say this for the sake of those men or women who fear they may be enticed into consenting to their violator’s lust, and think they should lay violent hands on themselves, and so prevent, not another’s sin, but their own.  But far be it from the mind of a Christian confiding in God, and resting in the hope of His aid; far be it, I say, from such a mind to yield a shameful consent to pleasures of the flesh, howsoever presented.  And if that lustful disobedience, which still dwells in our mortal members, follows its own law irrespective of our will, surely its motions in the body of one who rebels against them are as blameless as its motions in the body of one who sleeps.