Romans 6:12–14—Submit no longer to sin, a dethroned king.

Paul again speaks of sin as a ruling power whose reign and dominion have ended. As RC Sproul says, “Sin was the monarch on the throne of the heart, and we did obeisance to it. But that is no longer the case for the Christian.” Sin will dangle its passions in front of us, trying to reclaim its throne, but we must regard it as a usurper and bar it from access to our heart. We reckon ourselves dead to it.

Mortal body
Douglas Moo says “body” (soma) in verse 12 likely has the same general meaning as in verse 6, where it signifies the whole person. Some sins seek to satisfy lusts and appetites of the physical body whereas others incline our heart to hate, envy, covet, slander, dominate, blame, and be bitter. We overcome evil passions by cultivating passion for Jesus Christ, our holy Servant King who dethroned sin.

As in the case of body, “members” in verse 13, as Sproul says, “includes the mind, the heart, and everything else. Nothing of what makes up a human being is to be yielded as a tool or an instrument of sin.”

Weapons for righteousness
In the New Testament the Greek word for “instruments” is often translated as weapons. Paul uses the word twice in 2 Corinthians, first commending himself for wielding “the weapons of righteousness for the right hand and for the left” (6:7), and then asserting that “the weapons of our warfare are not of the flesh but have divine power to destroy strongholds” (10:4). In line with this military imagery, Marvin Vincent says Paul here in Romans is probably conceiving of “sin and righteousness as respectively rulers of opposing sovereignties… and enlisting men in their armies.”

We present our whole beings to God as those who are alive to him. How? Through worship, study of his word, prayer and meditation, service to others, forgiveness, compassion for those who hurt, and fellowship with others who have also been brought to life by him. When we do these things every part of our body, physical or immaterial, becomes a weapon for righteousness.

Change of Lordship
In the first part of verse 14 Paul summarizes his theme in this chapter: Sin shall have no have dominion (kyrieuō = lordship) over us. We should not be misled by Paul’s use of the future tense, for as Moo points out, “these words are to be understood as a promise that is valid for every believer at the present time: ‘sin shall certainly not be your Lord—now or ever!’” Our Lord is Jesus Christ, who by his death removed himself and us from the dominion of sin.

“Not under law but under grace”
This phrase takes us back to the subject of grace with which Paul opened this section with a question in verse 1. The short answer to that question, by the way, is that grace abounds in this new covenant age not by our sinning more but by Christ’s conquering of sin. We saw in 5:20 that law increases sin whereas grace “super-abounds” to overpower sin.

In verse 15 Paul will ask another question to introduce a warning and instruction to believers about obedience in the age of grace. This topic also points ahead to chapter 7 where Paul will dramatize the shortcomings of law as a way to deal with sin.