From the Discourse on the Resurrection

II. But if any one should venture to oppose this statement, and reply, that the apostle teaches that we hate not only the evil which is in thought, but that we do that which we will not, and we hate it even in the very act of doing it, for he says, The good which I would, I do not; but the evil which I would not, that I do; if he who says so speaks the truth, let us ask him to explain what was the evil which the apostle hated and willed not to do, but did; and the good which he willed to do, but did not; and conversely, whether as often as he willed to do good, so often he did not do the good which he willed, but did the evil which he willed not? And how he can say, when exhorting us to shake off all manner of sin, “Be followers of me, even as I also am of Christ?” Thus he meant the things already mentioned which he willed not to do, not to be done, but only to be thought of. For how otherwise could he be an exact imitation of Christ? It would be excellent then, and most delightful, if we had not those who oppose us, and contend with us; but since this is impossible, we cannot do what we will. For we will not to have those who lead us to passion, for then we could be saved without weariness and effort; but that does not come to pass which we will, but that which we will not. For it is necessary, as I said, that we should be tried. Let us not then, O my soul, let us not give in to the Evil One; but putting on the whole armour of God, which is our protection, let us have “the breastplate of righteousness, and your feet shod with the preparation of the Gospel (of peace). Above all, taking the shield of faith, wherewith you shall be able to quench all the fiery darts of the wicked. And take the helmet of salvation, and the sword of the spirit, which is the Word of God,” that you may be able to stand against the wiles of the devil; “casting down imaginations, and every high thing that exalts itself against the knowledge of Christ,” “for we wrestle not against flesh and blood;” for that which I do, I allow not; for what I would, that do I not: but what I hate, that do I. If then I do that which I would not, I consent unto the law that it is good. Now then it is no more I that do it, but sin that dwells in me. For I know that in me— that is, in my flesh— dwells no good thing. And this is rightly said. For remember how it has been already shown that, from the time when man went astray and disobeyed the law, thence sin, receiving its birth from his disobedience, dwelt in him. For thus a commotion was stirred up, and we were filled with agitations and foreign imaginations, being emptied of the divine inspiration and filled with carnal desire, which the cunning serpent infused into us. And, therefore, God invented death for our sakes, that He might destroy sin, lest rising up in us immortals, as I said, it should be immortal. When the apostle says, “for I know that in me— that is, in my flesh— dwells no good thing,” by which words he means to indicate that sin dwells in us, from the transgression, through lust; out of which, like young shoots, the imaginations of pleasure rise around us. For there are two kinds of thoughts in us; the one which arises from the lust which lies in the body, which, as I said, came from the craft of the Evil Spirit; the other from the law, which is in accordance with the commandment, which we had implanted in us as a natural law, stirring up our thoughts to good, when we delight in the law of God according to our mind, for this is the inner man; but in the law of the devil according to the lust which dwells in the flesh. For he who wars against and opposes the law of God, that is, against the tendency of the mind to good, is the same who stirs up the carnal and sensual impulses to lawlessness.

III. For the apostle here sets forth clearly, as I think, three laws: One in accordance with the good which is implanted in us, which clearly he calls the law of the mind. One the law which arises from the assault of evil, and which often draws on the soul to lustful fancies, which, he says, wars against the law of the mind. And the third, which is in accordance with sin, settled in the flesh from lust, which he calls the “law of sin which dwells in our members;” which the Evil One, urging on, often stirs up against us, driving us to unrighteousness and evil deeds. For there seems to be in ourselves one thing which is better and another which is worse. And when that which is in its nature better is about to become more powerful than that which is worse, the whole mind is carried on to that which is good; but when that which is worse increases and overbalances, man is on the contrary urged on to evil imaginations. On account of which the apostle prays to be delivered from it, regarding it as death and destruction; as also does the prophet when he says, “Cleanse me from my secret faults.” And the same is denoted by the words, “For I delight in the law of God after the inward man; but I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. O wretched man that I am! Who shall deliver me from the body of this death?” By which he does not mean that the body is death, but the law of sin which is in his members, lying hidden in us through the transgression, and ever deluding the soul to the death of unrighteousness. And he immediately adds, clearly showing from what kind of death he desired to be delivered, and who he was who delivered him, “I thank God, through Jesus Christ.” And it should be considered, if he said that this body was death, O Aglaophon, as you supposed, he would not afterwards mention Christ as delivering him from so great an evil. For in that case what a strange thing should we have had from the advent of Christ? And how could the apostle have said this, as being able to be delivered from death by the advent of Christ; when it was the lot of all to die before Christ's coming into the world? And, therefore, O Aglaophon, he says not that this body was death, but the sin which dwells in the body through lust, from which God has delivered him by the coming of Christ. “For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death;”so that “He that raised up Jesus from the dead shall also quicken your mortal bodies by His Spirit that dwells in you;”having “condemned sin” which is in the body to its destruction; “that the righteousness of the law” of nature which draws us to good, and is in accordance with the commandment, might be kindled and manifested. For the good which “the law” of nature “could not do, in that it was weak,” being overcome by the lust which lies in the body, God gave strength to accomplish, “sending His own Son in the likeness of sinful flesh;”so that sin being condemned, to its destruction, so that it should never bear fruit in the flesh, the righteousness of the law of nature might be fulfilled, abounding in the obedience of those who walk not according to the lust of the flesh, but according to the lust and guidance of the Spirit; “for the law of the Spirit of life,” which is the Gospel, being different from earlier laws, leading by its preaching to obedience and the remission of sins, delivered us from the law of sin and death, having conquered entirely sin which reigned over our flesh.