Catholic Commentary
The Moral Imperative: Do Not Let Sin Reign
12Therefore don’t let sin reign in your mortal body, that you should obey it in its lusts.13Also, do not present your members to sin as instruments of unrighteousness, but present yourselves to God as alive from the dead, and your members as instruments of righteousness to God.14For sin will not have dominion over you, for you are not under law, but under grace.
Romans 6:12–14 commands believers to refuse sin dominion over their mortal bodies and instead present themselves and their bodily members as instruments of righteousness to God. This is possible because grace, not law, is the governing power—grace provides the transformative indwelling of the Holy Spirit rather than mere judgment.
Sin is still campaigning for the throne of your body after baptism—and you must refuse it, again and again, because grace has already won the war.
Romans 6:12 — "Do not let sin reign in your mortal body"
Paul opens with a present-tense negative imperative (mē baseuetō), which in Greek signals the command to stop an action that may already be in progress, or to continuously resist a recurrent pressure. The word "reign" (basileuō) is loaded: Paul has just argued in Romans 5:14, 17, 21 that both sin and grace can "reign" as sovereign powers over humanity. Now he applies this royalist imagery directly to the body. The word "mortal" (thnētō) is deliberate and theologically precise: the body is still subject to death, still operating in the age of decay, and therefore still vulnerable to sin's gravitational pull even after baptism. This is not Gnostic dualism — Paul does not say the body is evil, but that it is mortal, and that mortality is the opening through which disordered desire (epithymiais, "lusts") makes its appeal. Sin, though dethroned in principle by baptism, still campaigns for the throne. The baptized must refuse to grant it the obedience (hypakouein) that belongs only to God.
Romans 6:13 — "Do not present your members… but present yourselves to God"
Paul now shifts from the image of a king and subject to that of a general and soldiers. "Present" (paristanete) is a military term for placing troops at a commander's disposal. "Members" (melē) — hands, eyes, tongue, feet — are the instruments through which the will enacts its allegiances. Paul draws a sharp antithesis: the same bodily members that can be weapons of unrighteousness (hopla adikias) can also be weapons of righteousness (hopla dikaiosynēs). The body is not neutral territory — it is a battlefield that will be occupied by one lord or another. Crucially, Paul commands believers to present themselves "as alive from the dead (hōsei ek nekrōn zōntas)." This participial phrase grounds the imperative in the indicative of baptism: we are to act as what we already are. The moral command is not a ladder by which we climb to grace, but the living out of a grace already received. This is the Catholic understanding of cooperation with justifying grace — not earning salvation, but enacting it.
Romans 6:14 — "Sin will not have dominion over you, for you are not under law, but under grace"
The verse shifts back to the indicative, now serving as the theological ground for the preceding imperatives. "Will not have dominion" (kyrieusei) recycles the lordship theme: sin is not your kyrios (lord). But why? Because the regime has changed. The phrase "not under law, but under grace" is one of the most contested in Pauline theology, and Paul himself anticipates the misreading in 6:15 ("Shall we sin because we are not under law?"). His meaning, in context, is not that moral obligation has been abolished, but that the power enabling moral transformation has changed. The Mosaic Law could identify sin and pronounce judgment, but could not supply the inner strength to overcome it (cf. Romans 7:7–12; 8:3). Grace, by contrast, is not merely pardon — it is the indwelling transformative power of the Holy Spirit. To be "under grace" is to live within a new economy where God's own life is the engine of righteousness. The imperative of verse 12 is possible because of the indicative of verse 14.
Typological Sense
The passage echoes Israel's liberation from Egypt. As Israel was delivered from Pharaoh's "reign" (basileuō was applied to Pharaoh in the Septuagint), so the baptized are delivered from the reign of sin. Yet Israel, once freed, was tempted to return to Egypt — to obey Pharaoh again. Paul's command "do not let sin reign" mirrors Moses' exhortations in Deuteronomy: freedom is a gift that must be chosen, again and again, at every fork in the desert road.
Catholic tradition reads these verses through the lens of the Council of Trent's careful distinction between the remission of sin in justification and the concupiscence that remains after baptism. Trent teaches that concupiscence — the disordered inclination toward sin — persists in the baptized but is "left for us to wrestle with" and is not itself sin when not consented to (Session V, Decree on Original Sin). This is precisely Paul's point in verse 12: the "lusts" (epithymiai) of the mortal body are not eliminated by baptism; they are dethroned. The baptized person retains genuine moral agency, which is why the imperative is possible and necessary.
St. Augustine, commenting on Romans 6, insists that grace does not abolish free will but perfects it: "God does not command the impossible, but in commanding, admonishes you both to do what you can and to ask for what you cannot" (De Natura et Gratia, 43). This Augustinian principle was enshrined in Catholic moral theology and echoed by the Catechism of the Catholic Church, which teaches that the grace of Christ "heals and elevates human freedom" (CCC 1742) and that man, "by free will, is capable of directing himself toward the good" (CCC 1705).
St. Thomas Aquinas, in his Commentary on Romans, notes that Paul's use of military language ("present your members as instruments") implies that the virtues are not passive states but active dispositions requiring repeated, deliberate exercise — connecting Pauline grace with the Aristotelian understanding of virtue as habituated freedom. Grace initiates; the will cooperates; the virtues consolidate that cooperation into stable character.
Pope St. John Paul II, in Veritatis Splendor (§§17–18), cites this Pauline passage to argue that Christian moral life is not reducible to rule-following (being "under law") but is a dynamic response to a personal encounter with the living God — a transformation of desire itself, not merely of behavior. "To be under grace" is to have one's deepest loves reordered by charity.
Paul's language of "members" as instruments is strikingly contemporary: in a digital age, the hands that scroll, the eyes that stream, the tongue that posts are precisely the "members" he has in mind. The passage calls contemporary Catholics to a concrete examination of conscience that is bodily and specific, not merely internal: What do I give my hands to do? Where do I direct my gaze? What does my voice build or destroy? The spiritual practice implied by verse 13 is something like a daily act of self-offering — a conscious "presenting" of oneself to God at the start of each day, which the Church has always expressed liturgically in the Morning Offering prayer.
Against the cultural assumption that desire is identity and that resisting any appetite is self-betrayal, Paul announces the opposite: freedom is not the indulgence of every impulse but the capacity to rule one's own house. The Sacrament of Confession is the practical sacramental instrument by which Catholics who have allowed sin to "reign" can re-enter the freedom of grace. Catholics are also called to remember verse 14 not as a comfort that excuses passivity, but as an empowerment: you are not merely trying harder — you are operating under a new and stronger regime.