The objection Paul answers here is a variation on the one he answered at the beginning of the chapter. If we are under grace and not under law, does that mean we can sin without consequence? He has already handled the logic of the resurrection to demolish one form of that thinking. Now he comes at it from a different angle.

"What then? Shall we sin because we are not under law but under grace? May it never be! Do you not know that when you present yourselves to someone as slaves for obedience, you are slaves of the one whom you obey, either of sin resulting in death, or of obedience resulting in righteousness?" (Romans 6:15–16).

The slave metaphor carries a brutal clarity. Everyone serves someone. There is no neutral territory, no person who answers to no one, no position outside of either sin's ownership or God's. This is not a spiritual insight Paul arrived at by meditation. It is an observation about the mechanics of moral life. What a person habitually yields to is what owns him. The man who cannot say no to his anger is that anger's slave. The man who cannot say no to his appetites is their slave. And slaves follow the nature of the master they serve — one ends in death, one in righteousness.

The gospel does not offer freedom from service. It offers transfer of ownership. "But thanks be to God that though you were slaves of sin, you became obedient from the heart to that form of teaching to which you were committed, and having been freed from sin, you became slaves of righteousness" (Romans 6:17–18). The Christian is not a person who has been liberated from all constraint. He is a person who has changed masters. He was given to sin; now he has been given to righteousness. And the transfer happened not merely at the level of external behavior — it happened from the heart. The obedience Paul describes here is not grudging compliance. It is what the new nature, shaped by the gospel, produces in a person who has genuinely received it.

Paul draws the contrast out to its end with the sharpness of a man who has seen sin's destruction up close. "For just as you presented your members as slaves to impurity and to lawlessness, resulting in further lawlessness, so now present your members as slaves to righteousness, resulting in sanctification" (Romans 6:19). Sin compounds itself. Lawlessness does not plateau; it progresses. The man who yields to it regularly finds himself going further than he intended to go, because sin is not static. It is progressive. Righteousness follows the same logic in the other direction: each act of obedience shapes the person toward more obedience, and the direction of travel is toward holiness.

The contrast reaches its destination in one of the most memorable sentences in the letter. "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord" (Romans 6:23). Paul has been using the wage metaphor since chapter four — the worker who earns his pay as something owed, rather than as a favor. Here the metaphor reaches its point. Sin pays. It pays exactly what it promised and exactly what it always pays — death. The tragic thing about sin's paycheck is that it is never a surprise. Everyone who has lived under sin's employment long enough has seen the direction it runs.

The free gift operates differently. God does not owe anyone eternal life. It is not earned, not deserved, not the product of having finally crossed some threshold of performance. It is given. Freely. In Christ. And the one who has received it has received something no wage system could ever produce.

This is the spine of chapter six: not that the Christian is now exempt from obligation, but that the nature of his obligation has changed. He is no longer owned by what kills him. He belongs to the One who raised His Son from the dead, and the direction of that life is not death but glory.