The Law in Romans, and Paul’s thought generally, is complex.
On the one hand, it is promissory: it looks to the future; it plays the part in the story of prophet. It points away from itself to the coming work of God in Christ.
But on the other hand, Law is tied to sin as what indicates Israel’s own guilt.
And with sin and guilt, the Law brings wrath.
Why must the promise not be realized through the Law itself, but outside the Law in the Christ event? “Because the Law brings wrath, but where there is no Law, neither is there transgression” (Romans 4:15).
By saying this much, Paul reiterates in ch. 4 of Romans what he had said in chs. 1-3: that the Law plays the role of making Israel guilty of what Israel could assume the Gentile world was guilty of: failure to honor and glorify God. And, it puts it in the same position as deserving of wrath that Rom 1:18 tells us is the condition of the Gentile world as well.
In the second half of Rom 5, Paul begins the extensive work of rewriting the Law’s role in the story of Israel.
What came with, apparently, promises of righteousness and life, is at first simply put to the side. What is determinative for the destiny of humanity is not the Law given to Israel but, instead, the actions of two men: Adam and Christ (Rom 5:12-19). Adam’s transgression unleashed the reign of sin and death; Jesus’ obedience inaugurates the reign of grace.
God’s grace, life, the gift of righteousness–all the things that one might have thought the Law was scripted to give, are instead provided by the obedient, dying Messiah.
So what, then, are we to make of the Law if it does not, in fact, work the life that it seemed to promise?
5:20: The Law came in in order that it might increase the transgression.
The purpose of the Law, in this case, is to make Israel a microcosm–not of the saving act of the Messiah in obedience, but–of the failure of Adam.
But here’s the point: though this was a purpose of the Law, it was only the penultimate purpose of God. Into this realm of increasing sin, the grace of God abounded more. In the context, this grace has already been defined: the super-abounding grace of God is what comes in the death of Jesus.
As Rom 1:18 had told us that the revelation of God’s righteousness depends on the revelation of God’s wrath; as Rom 3 had told us that God’s righteousness is demonstrated by Israel’s unrighteousness, so here we hear that God’s grace in Christ comes right to the place where sin was most strengthened by transgression.
The final purpose of this was that the increase of sin was that a new reign might be established in its place: the reign of grace that comes through Christ.
How is it that this “holy, righteous, and good” law ends up playing such a dark role in the story?
In short, chs. 6-7 tell us, the problem is that the Law is a loyal subject, or a weapon. Whoever is lord of its realm, the Law faithfully serves. The paradox of Paul’s gospel message, as it rewrites the role of the Law in the story of Israel, is that to be freed from the Law is also to be freed from Sin (Rom 6:14).
When it comes to a world under the reign of sin, the law is used by that lord to bring about death. To be under Law is to be under Sin, and ultimately to be under Death.
The chart below ( from Unlocking Romans) shows how the very language Paul uses to speak of sin and death in Rom 6 is repeated as he talks about the Law in Rom 7:
The only way to break free from the enslaving force of sin, as it uses the Law for its purposes, is through the death and resurrection of Jesus (Rom 7:1-6). With this cosmic intervention of God comes the Spirit, who enables us to do what the Law was powerless to do: bear fruit for God (Rom 7:5-6).
The bottom line: The Law comes as a Spiritual entity to a fleshly people without the power to make that people Spiritual. Because of this lack of transforming power, it is used by the governing power of the world, sin, in order to work transgression, sin, and death.
But when the Spirit of the resurrected Christ comes, the Spirit who has power even to give life to dead flesh (Rom 1:4), God shows that there is a way to be made righteous, to know life, to escape from wrath. The resurrected Christ performs the role that, one would have thought, was the role of Torah in Israel’s story: life-bringer, righteous-maker.