Thomas Aquinas Commentary Romans 6:12-18

"Let not sin therefore reign in your mortal body, that ye should obey the lusts thereof: neither present your members unto sin [as] instruments of unrighteousness; but present yourselves unto God, as alive from the dead, and your members [as] instruments of righteousness unto God. For sin shall not have dominion over you: for ye are not under law, but under grace. What then? shall we sin, because we are not under law, but under grace? God forbid. Know ye not, that to whom ye present yourselves [as] servants unto obedience, his servants ye are whom ye obey; whether of sin unto death, or of obedience unto righteousness? But thanks be to God, that, whereas ye were servants of sin, ye became obedient from the heart to that form of teaching whereunto ye were delivered; and being made free from sin, ye became servants of righteousness." — Romans 6:12-18 (ASV)

1. After showing that we should not remain in sin and that we have the capacity for this, the Apostle concludes with a moral exhortation.

   Concerning this, he does three things:

   1. He proposes an admonition.
   2. He assigns a reason for it, at the words, for sin shall not have dominion over you.
   3. He raises and solves a question, at the words, What then? Shall we sin.

   In regard to the first point, he does two things:

   1. He proposes the admonition.
   2. He clarifies it, at the words, so as to obey.

2. First, therefore, he says: we have said that our old self was crucified once, so that the body of sin might be destroyed. This means that the power of sin has been so weakened that it cannot rule us. Let not sin therefore reign in your mortal body any longer.

   He does not say, “let sin not be in your mortal body,” because as long as our body is mortal—that is, bound to the necessity of death—it is not possible for sin not to be in our body, meaning the inclination to sin. But since we have been freed from the kingdom of sin by God, we must struggle so that sin does not recover the dominion it has lost in our body. This is what he says: let not sin reign in your mortal body. This is something we must be on guard against as long as we wear this mortal body: the corruptible body is a load upon the soul .

3. Then, when he says, so as to obey, he clarifies this admonition.

   It should be noted that sin reigns in a person in two ways.

   1. First, sin reigns through the internal consent of the mind. To remove this, he says, so as to obey its lusts. For it is by obeying the passions of sin with our minds that sin reigns in us: do not go after your lusts .

   2. Second, sin reigns in us through the performance of the sinful act. To exclude this, he adds, neither yield your members to sin as instruments of iniquity, that is, as instruments for committing sin. For when a person commits sin through his members, he yields to sin. In this way, he seems to fight to restore sin’s dominion, which grows in us through the habit of sinning: they went down to hell with their weapons (Ezekiel 32:27).

4. Then, when he says, but yield yourselves to God, he urges them to the opposite, namely, to yield themselves to God.

   He addresses this first with regard to the internal faculties, saying, but yield yourselves to God by submitting your mind to God: and now, Israel, what does the Lord your God require of you, but to fear the Lord your God, to walk in all his ways (Deuteronomy 10:12). You should do this as those who are alive from the dead, that is, as those led from the death of sin to the life of grace. Hence, it is fitting that since he died for all, those who live might no longer live for themselves but for him who for their sake died and was raised (2 Corinthians 5:15).

   Second, he addresses this with respect to outward actions; hence he says to yield your members... to God as instruments of justice with which to fight against God’s enemies: put on the whole armor of God, that you may be able to stand against the wiles of the devil (Ephesians 6:11).

5. Then, when he says, for sin shall not have dominion over you, he gives the reason for this admonition.

   Someone might excuse himself by alleging that sin’s dominion is an obstacle to obeying the admonition. But the Apostle excludes this, saying, for sin will not have dominion over you, provided you begin to resist sin and yield yourself to God: draw near to God and he will draw near to you. Resist the devil and he will flee from you (James 4:8). It is as if to say: you can follow my admonition, because you will not find sin dominating and holding you. For we have been freed by Christ, as John says: if the Son makes you free, you will be free indeed (John 8:36).

6. Then he clarifies what he had said, saying, for you are not under the law, but under grace.

   Here it should be noted that he is not speaking of the law only in regard to its ceremonial precepts, but also its moral precepts. For a person is said to be "under the law" in two ways.

   In one way, a person is under the law by being voluntarily subject to its observance. Even Christ was under the law in this way, according to Galatians: born under the law (Galatians 4:4), because he observed the law—not only the moral but also the ceremonial precepts. The faithful in Christ are under the law in this way with respect to the moral precepts, but not the ceremonial ones.

   In another way, a person is said to be under the law as if compelled by it. In this sense, one is under the law when he does not obey it voluntarily from love but is compelled by fear. Such a person lacks grace, which, if it were present, would incline the will to observe the law and fulfill its moral precepts from a motive of love. Therefore, as long as one is under the law in such a way that he does not fulfill it voluntarily, sin has dominion over him. As a result, such a person’s will is inclined to choose what is contrary to the law. But through grace, this dominion is removed. Consequently, a person observes the law not as one existing under the law but as one who is free: we are not children of the slave but of the free woman, by the freedom with which Christ has set us free (Galatians 4:31).

7. This grace, which makes people freely obey the law, was not conferred by the sacraments of the old law; rather, Christ’s sacraments conferred it. Consequently, those who submitted themselves to the ceremonies of the law were not, in terms of the power of those sacraments, under grace but under the law, unless they obtained grace through faith.

   But a person who submits to Christ’s sacraments obtains grace from His power, so as not to be under the law but under grace, unless they enslave themselves to sin through their own fault.

8. Then, when he says, What then?, he raises a question in response to what he has said.

   Concerning this, he does three things:

   1. He raises the question.
   2. He answers it, with the words, God forbid! Do you not know.
   3. He shows how unfitting it would be to misinterpret his statement, with the words, but thanks be to God.

9. Regarding the first point, it should be noted that his statement could be falsely interpreted to mean that Christ’s faithful are not under the law in the sense of being obligated to obey its moral precepts. If this were true, it would follow that Christ’s faithful could lawfully commit sin and act against the moral precepts.

   Therefore, in this context he raises the question: What then? Shall we sin—that is, shall we act against the moral precepts—because, as has been said, we are not under the law, but under grace? The Apostle rejects this interpretation in Galatians: for you were called to freedom, brethren; only do not use your freedom as an opportunity for the flesh (Galatians 5:13).

10. In the same way, he answers here, God forbid that we should sin because we have been set free from the law. For if we were to sin, we would once again be reduced to the slavery of sin.

    Hence, he continues, Do you not know that to whomever you yield yourselves as servants to obey, you are servants of the one you obey? For obedience is a debt that slaves owe their masters: slaves, be obedient to your earthly masters (Ephesians 6:5). Therefore, when someone obeys another, he admits by his obedience that he is that person's slave.

    But different masters are obeyed for different rewards. The one who obeys sin is led to death through the slavery of sin. This is what he means by, whether of sin unto death—that is, you are its slaves by obeying it, leading to the eternal damnation of the one who does so. Concerning this death it is said: he who conquers shall not be hurt by the second death (Revelation 2:11). But the one who obeys God is made a slave of this obedience, because through the habit of obeying, the mind is inclined more and more to obedience and as a result achieves holiness. Therefore, he says, or of obedience unto justice, meaning obedience to the divine precepts, which leads to justice: the doers of the law will be justified (Romans 2:13).

    Sin and obedience are fittingly presented as opposites because, as Ambrose says, sin is a transgression of the divine law and a disobedience against the heavenly commands.

11. Then, when he says, but thanks be to God, he shows the folly of obeying sin and thereby returning to its slavery. He does this in two ways:

    1. First, by considering the benefit we have received. If someone is freed from slavery by another’s grace, it is unfitting to freely subject oneself to slavery again. Therefore, since we have been freed from sin by the grace of God, it is unfitting to willingly return to the slavery of sin.
    2. Second, by considering the state into which we were led after being freed from sin, namely, that we are slaves to justice. It is not lawful for a slave to subject himself to the dominion of an opposing master; therefore, if we have been made slaves of justice, it is not lawful to return to the slavery of sin.

12. The Apostle touches on both of these considerations when he says: I thank God, and you should also thank God, that you were the servants of sin, because he who commits sin is a slave to sin (John 8:34), but you have obeyed from the heart. This obedience is through believing, as in for obedience to the faith among all nations (Romans 1:5), and this not as if compelled, but from the heart, for with the heart one believes for justice (Romans 10:10).

    You have obeyed that form of doctrine to which you were delivered, that is, the doctrine of the Catholic faith: follow the pattern of the sound words that you have heard from me (2 Timothy 1:13). "To which you were delivered" means you gave yourselves entirely: but first they gave themselves to the Lord and to us by the will of God (2 Corinthians 8:5).

    And by this, being then freed from sin, it is not fitting to desert justice: you were bought with a price (1 Corinthians 7:23) and are not your own.