Therefore, Paul continued, do not let sin reign in your mortal body so that you obey (ὑπακούειν, a form of ὑπακούω) its desires (ἐπιθυμίαις, a form of ἐπιθυμία). This is clearly Step #2 how to experience the credited righteousness of God apart from the law, namely, the righteousness of God through the faithfulness (πίστεως, a form of πίστις) of Jesus Christ for all who believe (πιστεύοντας, a form of πιστεύω). I think the next verse amplifies how one goes about not letting sin reign in one’s mortal body, and do not present your members to sin as instruments to be used for unrighteousness, but present yourselves to God as those who are alive from the dead and your members to God as instruments to be used for righteousness. So I am picturing something like this:
Step #2 to experience the righteousness of God through the faithfulness of Jesus Christ for all who believe.
|…do not let sin reign in your mortal body so that you obey its desires.
Romans 6:12 (NET)
|…not present(ing) your members to sin as instruments to be used for unrighteousness…
Romans 6:13a (NET)
|…present(ing) yourselves to God as those who are alive from the dead and your members to God as instruments to be used for righteousness.
Romans 6:13b (NET)
It sounds so simple, but there is no door marked “sin” beside a door marked “God” where I might present myself for service. This transaction, if you will, takes place in the deepest, darkest places of an individual born from above, born of flesh and born of the Spirit, moment by moment. In fact, Paul described this individual as a house divided, For the flesh has desires that are opposed to the Spirit, and the Spirit has desires that are opposed to the flesh, for these are in opposition to each other, so that you cannot do what you want. So then, Paul concluded in Romans 7, with the mind I myself serve the law of God, but with the flesh the law of sin.
There is a cartoon image of a human being with a little devil i on one shoulder whispering in one ear and a little angel i whispering in the other. In the center between them am I, writ large, the Master of My Fate, choosing sin or righteousness. With this self-image I discounted the value of Step #1—to consider (λογίζεσθε, a form of λογίζομαι) [myself] dead (νεκροὺς, a form of νεκρός) to sin, but alive to God in Christ Jesus—as I magnified the importance of Step #2, not to let sin reign in [my] mortal body so that [I] obey[ed] its desires. So I set out not to break, or to keep, the laws that define sin, and unwittingly played directly into sin’s strength: the power (δύναμις) of sin is the law. Had I paid more attention to faith I might have grasped Paul’s next point sooner. For sin will have no mastery over you, because you are not under law (ὑπὸ νόμον) but under grace (ὑπὸ χάριν).
This personification of sin was not magical thinking on Paul’s part. What he was writing about actually becomes clearer in Romans 7. The sin that will not master the one who believes in Jesus is nothing other than the old man that was crucified with him so that the body (σῶμα) of sin would no longer dominate us. I am not refereeing a battle of wills between a little devil i and a little angel i. I am the old man of sin, or I am the new man of the Spirit. Both are in this body (σῶμα). Both want control. The old man was crucified by faith in Jesus Christ. The new man was created out of nothing through faith in Jesus Christ. Believing in Jesus Christ is far more important than anything either I, the dead and dying old man or the initially alien new man, might do. And I am persuaded that the illusion that I am a third something choosing between them is nothing more than the pride of life (1 John 2:15-17 NKJV).
Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world—the lust of the flesh, the lust of the eyes, and the pride of life—is not of the Father but is of the world. And the world is passing away, and the lust of it; but he who does the will of God abides forever.
What then? Paul continued. Shall we sin because we are not under law (ὑπὸ νόμον) but under grace (ὑπὸ χάριν)? Absolutely not! Paul’s reasoning here was a truism, a simple matter of definition. Do you not know (οἴδατε, a form of εἴδω; i.e., know by seeing) that if you present yourselves as obedient (ὑπακοήν, a form of ὑπακοή) slaves, you are slaves of the one you obey (ὑπακούετε, another form of ὑπακούω), either of sin [the desire of the old man] resulting in death, or obedience (ὑπακοῆς, another form of ὑπακοή) [the desire of the new man] resulting in righteousness?
I am convinced that words like obey, obedient, and obedience with their insistent emphasis on doing are part of the things of this world, the pride of life where I am the Master of My Fate, choosing to do the good or to do the evil. In Greek the word translated obey is ὑπακούω, to hear under, in other words to trust. The word translated obedient or obedience is ὑπακοή, attentive hearkening, in other words to believe. These are other words, perhaps even better words, for faith and believe than πίστις and πιστεύω, for no one could mistake them for πίστεως μόνον (faith alone), or dead faith. And again, this makes perfect sense if one is interested in experiencing the righteousness of God…revealed in the gospel from faith (πίστεως, a form of πίστις) to faith (πίστιν, another form of πίστις), just as it is written, “The righteous by faith (πίστεως, a form of πίστις) will live.”
But thanks be to God that though you were slaves to sin, you obeyed (ὑπηκούσατε, another form of ὑπακούω) from the heart that pattern of teaching you were entrusted to, and having been freed from sin, you became enslaved to righteousness. So I ὑπακούω, hear under, trust, the word of God rather than becoming ὑπακοή to, hearkening attentively to, believing, the promptings and desires of the old man, the man of sin created in the image of Adam. Of course I will do things. But now those things, rather than being the acts of an actor, will flow naturally from who I hear under (trust, hearken attentively to, believe) through who I am (the new man born of the Spirit in the image and likeness of God) and then out into the world.
The writer of Hebrews described it this way: Consequently a Sabbath rest remains for the people of God. For the one who enters God’s rest has also rested from his works, just as God did from his own works. Even the law comes into sharper focus: Remember the Sabbath day, to keep it holy, not for a day of the week but for the remainder of a lifetime. And Jesus’ word is fulfilled: But the one who practices the truth comes to the light, so that it may be plainly evident that his deeds have been done in God. It also explains Jesus’ rather obstinate insistence on doing good on the Sabbath day, despite the bitterness and resentment it aroused: So it is lawful to do good on the Sabbath.
The writer of Hebrews continued with the following warning (Hebrews 4:11-13 NET):
Thus we must make every effort to enter that rest, so that no one may fall by following the same pattern of disobedience [i.e., fearfully refusing to enter the promised land]. For the word of God is living and active and sharper than any double-edged sword, piercing even to the point of dividing soul from spirit, and joints from marrow; it is able to judge the desires and thoughts of the heart. And no creature is hidden from God, but everything is naked and exposed to the eyes of him to whom we must render an account.
Paul realized he had not yet explained what would be explained in the next chapter. He recognized that his readers may misunderstand his words (Romans 6:19-23 NET).
(I am speaking in human terms because of the weakness of your flesh.) For just as you once presented your members as slaves to impurity and lawlessness leading to more lawlessness, so now present your members as slaves to righteousness leading to sanctification. For when you were slaves of sin, you were free with regard to righteousness. So what benefit did you then reap from those things that you are now ashamed of? For the end of those things is death. But now, freed from sin and enslaved to God, you have your benefit leading to sanctification, and the end is eternal life. For the payoff of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.
 John 3:6 (NET)