Paul’s Use of Scripture in Romans 3
Originally published on the Biblical Horizons blog c. 2014
It has always been recognizably important to pay attention to the Old Testament quotations we find in the New Testament, but in recent years, it has become even more clear that one must take into account the extended context of the passage cited, not simply the words directly quoted. This is understandable: unlike our situation, the ancient world largely communicated texts as an oral culture, and nobody footnoted.
But it is understandable on an even more important level: the New Testament writers are not manufacturing a de novo religion; they are drawing upon an inspired and authoritative text that has come to new light with the advent of Christ and the Spirit. (Indeed, this is what Paul says almost directly in 2 Corinthians 3.) And if this is the case, we can be sure that — no matter what our untrained eyes may lead us to believe at first glance — the writers of the New Testament were contextual and faithful to the Scriptures from which they drew. Our failure to recognize this stems, not from our superior training in hermeneutics, but from the poverty and weakness of our biblical understanding.
In the case of Romans 3, we have one of the heaviest concentrations of biblical citations to be found within the Pauline corpus. This means that proceeding to define terms and phrases must not be done in a vacuum; we must investigate the passages Paul cites.
1. Romans 3:1–8
The Righteousness of God
One of the most thematic phrases that we find in Romans 3 is "the righteousness of God" (or, with the pronoun, "His righteousness"). Indeed, this chapter has the highest concentration of that phrase in all of Scripture; it appears no less than five times in a span of barely more than twenty verses ( 3.5, 21, 22, 25, 26). It appears elsewhere in Romans at the programmatic point of 1.17, as well as 10.3 (twice). Elsewhere in Paul it appears only in 2 Corinthians 5.21, although apparently similar phraseology ("righteousness from God") can also be found in 1 Corinthians 1.30 and Philippians 3.9. It is very clear that the phrase, therefore, is clustered at this particular point.
Why is this so important? As it happens, the overwhelming majority of passages Paul quotes or cites in Romans 3 mention divine righteousness somewhere in the context. This can scarcely be accidental. Although we cannot engage all of these texts in depth in this particular post (perhaps we can come back to the other texts as we continue), I wish to focus for the moment upon Psalm 51, which is the first text Paul directly quotes in Romans 3 (verse 4 is a quotation of Ps 51.4b).
Following immediately upon the heels of his quotation of the penitential psalm (David's confession following his adultery with Bathsheba and murder of Uriah), Paul provides his first use of our phrase (Rom 3.5a) since his summary introduction in 1.17: "But if our unrighteousness serves to commend the righteousness of God, what shall we say?"
Divine righteousness appears in the context of Paul's quotation in Ps 51.14: "Deliver me from bloodguiltiness, O God, O God of my salvation, and my tongue will sing aloud of Your righteousness" (LXX dikaiosunhn sou). The divine righteousness in this first biblical quotation of Romans 3, therefore, is revealed in God's saving mercy; indeed, it is virtually synonymous with salvation.
Because we will be going through a number of further passages, I won't dance around further on the issue of the Old Testament context of the righteousness of God at this point.
"Against You, You Only, Have I Sinned...."
Instead, I want to draw attention to one further feature of the connection between Romans 3 and Psalm 51.
It is frequently assumed that Romans 3.1-8 is an aside, a parenthetical remark within Paul's argument. On this view, in terms of the language of 3.9, Paul charges that all the Greeks are "under sin" in Romans 1, and all the Jews in Romans 2. Thus between chapter 2 and 3.9 is a sort of respite in his argument where he imposes a parenthesis.
I don't think so.
While it is true that Romans 2 does turn particular attention to the Jew, Paul only raises questions there (2.21-22), unless we take the very general statement in 2.23-4 to comprise his charge. But the specific charges of 2.21-22 are surely extreme examples that every Jew would be forced to agree with: yes, such heinous crimes would indeed be serious covenant-breaking. But Paul's contemporaries, for the most part, would feel secure that they were beyond the reach of such charges.
I suggest that Paul insinuates a further and more far-reaching charge in 3.1-8, and this is opened up in no small degree by his employment of Psalm 51.
Paul begins by saying that the Jew has advantage, that circumcision has value, precisely because they were entrusted (episteuthesan, from the pist- root common with the familiar faith) "the oracles of God" (ta logia tou Theou). What is Paul referring to with this phrase? Most assume he is alluding to the law, but that does not seem likely; he invariably prefers to identify that as nomos.
More likely, Paul is referring back to where he began his letter: the gospel of God was promised beforehand through His prophets in the holy Scriptures - the gospel of God's Son (1.1-3). If this is so, we could well take 3.3 to read, "For what if some did not believe," rather than the usual "what if some were unfaithful?" (Either is equally possible from the Greek.) "Does their unbelief [/faithlessness] nullify the faithfulness [pistis] of God?"
If we are on the right track, Paul's great charge against his contemporary kinsmen is not that they have broken this and that aspect of the Mosaic law, but that they have disbelieved the Messiah who has come in fulfillment of the prophetic words. (I'm well aware that this is going to chafe with common readings of 3.19, but we will arrive there later.)
Now, how does this reading interface with Paul's biblical quotation in 3.4?
Paul responds to his own rhetorical question by introducing his quotation thus: "By no means! Let God be true, but every man a liar, just as it is written, 'So that You may be justified (dikaiothes) in Your words (logoi), and overcome in Your judgment.'"
Just an aside: in these early chapters of Romans, Paul repeatedly juxtaposes something from God's side over against something from man's. The righteousness of God is revealed from faith — to faith. The prepositions indicate "faith" [pistis] coming from two directions.
The righteousness of God is set into a context where God counts faith as righteousness. And here, in the quotation, Paul introduces the justification of God in preparation for a discussion of the justification of men; as is the case with the other juxtapositions, the justification of God and the justification of men must meet, and only God can effect the union.
Now, back to Paul's use of Psalm 51. It may be that Paul is connecting the divine logoi with the logia of promise he has mentioned in verse 2. But there is something even more intriguing here: the first part of the verse he has quoted reads thus: "Against You, You only, have I sinned and done what is evil in Your sight, so that You may be justified in Your words and blameless in Your judgment." Psalm 51.4a is a confession of a very direct sin against Yahweh Himself.
Moreover, as we have seen, Psalm 51.14 introduces the divine righteousness with a confession of bloodguilt: "Deliver me from bloodguiltiness, O God, O God of my salvation."
Given the total picture, it seems likely to me that Paul is providing a reminder that in failing to believe her Messiah, Israel had not only fallen short of the promises, but had sinned directly against God Himself ("against You, You only, have I sinned"), and that this sin had indeed extended to becoming guilty of the very blood of God's Messiah.
While it is common to read Israel's sin as having to do with a universal failure to perfectly keep the law, it is important to note that the reading I have provided here comports fully with Paul's own depiction of Israel's fall later in this epistle. In 9.32–33, Israel stumbles over the stumbling stone — which is Christ. Likewise, in chapter 11, this stumbling (11.9, 11) becomes the occasion of the "ungrafting" of the bulk of Israel (11.17ff).
All of this, I suggest, provides prima facie evidence that Paul is not busy charging Israel with unspecified offenses against the law of Moses. He has a much more serious charge: Israel has been faithless and unbelieving with the word of hope entrusted to her; indeed, she has stumbled over her Messiah and become guilty of His blood.
"Under Sin"
Lest it be thought that my reading "de-universalizes" Paul's indictment (it does not; it just takes the focus away from the law), I wish to point out one further commonality between Romans 3 and Psalm 51. Immediately after 51.4, which Paul quotes, David goes on to say, "Behold, I was brought forth in iniquity, and in sin did my mother conceive me" (51.5). The specific bloodguiltiness to which David confesses is thus an outgrowth of a more basic native condition.
This matches what Paul does in Romans 3, as well. For immediately after the insinuations of 3.1-8, he concludes that the charge is that both Jews and Greeks "are under Sin" (3.9). Without yet engaging the nature of Paul's universal language employed in 3.10-18, we can at least say that the native human condition, common to both Jew and Gentile, is one of bondage to an evil master.
2. Romans 3:9–18
So far in our look at Paul's use of Scripture in Romans 3, we have focused upon how Psalm 51, from which the apostle quotes in verse 4, determines and shapes our reading of 3.1-8. We have also noted that the psalm contains a reference to divine righteousness (Ps 51.14), where it refers to God's salvific activity.
We move on now to the next subsection, and begin our consideration of Romans 3.9-20. What are these passages from which Paul quotes? What do they contribute to our understanding of Paul's train of thought?
The Catena
3.9. In verse 9, Paul sets up his great catena of quotations, which speak relentlessly of the evil of men. In 3.10-18, he draws on Psalm 14/53, Psalm 5, Psalm 140, Psalm 10, Isaiah 59, and Psalm 36. Thus, five of the six quotations are drawn from the Davidic psalms, in addition to the earlier citation of Psalm 51.
3.10-12. It is not immediately clear where Paul is drawing from in his opening salvo in 3.10: "None is righteous, no, not one." It bears some resemblance to Ecclesiastes 7.20, which shares the righteous language employed here, but the form of the verse is rather different. It therefore seems more likely that Rom 3.10 is Paul's version of Psalm 14.1b ("there is none who does good"), particularly since he continues on (in vv 11-12) from here to quote from the verses immediately following (Ps 14.2-3). Interestingly, however, rather than using the LXX's terminology of "doing good" (chrestoteta in Psalm 14.1; agathon in the parallel in Psalm 53), in keeping with his theme, Paul deploys righteous.
What is the overall context of Psalm 14/53? In these parallel psalms, David's complaint is against "the children of man," but contrary to what we may expect, this is not a universalization. These wicked ones are set over against "my people," whom the wicked devour like bread (14.4). Yet these wicked "are in great terror, for God is with the generation of the righteous" (14.5; cf the contrast between the terrified wicked and "you" in 53.5). In Psalm 53, the judgment against the wicked is that God puts them to shame, for He has rejected them (53.5; note the "shame" themes of Romans, e.g. 9.33, 10.11, both drawing on Is 28.16). The psalm continues by making a plea that Yahweh would bring salvation for Israel (14.7; 53.6). Quite unexpectedly, then, David has a group of people identified as the righteous, and he anticipates divine salvation on their behalf.
3.13. In Rom 3.13a-b ("their throat is an open grave; their tongues speak deceit"), Paul is quoting from Psalm 5.9 (5.10 LXX). Here again we find divine righteousness in the immediate context: "Lead me, Yahweh, in Your righteousness because of my enemies; make Your way straight before my face" (Ps 5.8). Here God's righteousness is appealed to as David's defense against his enemies. David contrasts himself to the wicked; unlike the boastful who will not stand before Yahweh (5.5), and the liars whom He will destroy (5.6), David says confidently that "through the abundance of Your mercy (Heb chesed)," he will enter God's house (5.7). Regarding the wicked of whom Paul speaks in Romans (from Ps 5.9), David calls upon God to make them bear their guilt; that He would cast them out for their transgression and rebellion against God (5.10). In contrast, "let all who take refuge in You rejoice; let them ever sing for joy, and spread Your protection over them, that those who love Your name may exult in You" (5.11 ESV). And once again, David is unafraid to identify such favoured ones as "righteous": "For You bless the righteous, Yahweh; You surround him with favour as with a shield" (5.12).
Romans 3.13c ("the poison of asps is under their lips") is a quotation of Psalm 140.3 (139.4 LXX). In this psalm, too, David makes a clear distinction between himself and evil men ("Deliver me, Yahweh, from evil men," verse 1), and the contrast again culminates in his identification of Yahweh's afflicted ones as "the righteous": "I know that Yahweh will execute the judgment of the afflicted, the justice of the needy. Surely the righteous shall praise Your name; the upright shall dwell [or sit] in Your presence" (140.13). It is to be noted that whereas Psalm 5.12 speaks of the righteous in the singular, in this case David employs the plural.
3.14. "Whose mouth is full of cursing and bitterness" is a quotation from Psalm 10.7 (9.28 LXX). It is of special interest that the Septuagint treats Psalms 9 and 10 as a single psalm, as the versification reflects. In Ps 9.4, David confesses that Yahweh has maintained David's just cause and gave righteous judgment from His throne. Indeed, Yahweh judges the world with righteousness (9.8; cf Rom 3.5-6!). This righteous judgment is reflected in Yahweh's giving Himself as a fortress for the oppressed (9.9); because Yahweh does not forget the cry of the afflicted, David is confident to entreat Yahweh for grace and salvation (9.12-14). Thus the theme of divine righteousness returns here in connection with Yahweh's justice, whereby He will relieve and save the afflicted, those who know His name and trust in Him (9.10), but brings the wicked to everlasting ruin and blots out their name (9.5-6). He is the helper of the fatherless (10.14), but can be called upon to call to account the wicked (10.15); those who overrun His land and afflict His people will perish and strike terror no more (10.16-18).
3.15-17. "Their feet are swift to pour out blood" in verse 15 breaks the chain of Psalm quotations; it is a somewhat abbreviated rendering of Isaiah 59.7a ("their feet run upon wickedness, swift to pour out blood"). Verses 16-17 is a quotation from Isaiah 59.7b-8a: "Their thoughts are thoughts of iniquity; desolation and destruction are in their highways. The way of peace they do not know" (ESV). The theme of bloodguiltiness, raised in Psalm 51, is again in the context here: "your hands are defiled with blood and your fingers with iniquity" (Is 59.3). The despairing assessment is that justice is far away, "and righteousness does not overtake us" (59.9). The chapter gradually shifts from this bleak perspective to that once again recurring theme of divine righteousness: "Yahweh saw it, and it was evil in His eye that there was no judgment. And He saw that there was no man, and He was appalled that no one interceded; then His own arm saved for Him, and His righteousness supported Him" (Is 59.15b-16). Once again divine righteousness entails salvation for Yahweh's people and destruction of His enemies; as 59.17 adds, "He put on righteousness as a breastplate, and a helmet of salvation on His head; He put on garments of vengeance for clothing, and wrapped Himself in zeal as a cloak" (ESV). This preparation results in repayment of His adversaries according to their deeds (59.18), and the arrival of the Redeemer "to those in Jacob who turn from transgression" (59.20), culminating in the new covenant promise of 59.21: "And I, this is my covenant with them... My Spirit that is upon you, and My words that I have put in your mouth, shall not depart from your mouth, or from the mouth of your seed, or from the mouth of the seed of your seed... from now until forever."
3.18. At the close of his great catena, Paul returns again to the Davidic psalms: "There is no fear of God before their eyes," taken from Ps 36.1 (35.1 LXX). As in several other of the psalms cited by Paul, here again the wicked flatter themselves that their evil will not become known nor judged (36.2). But once again the violence of the wicked (implicitly, against the righteous) is set over against Yahweh's chesed, His covenant mercy, which extends to the heavens (36.5); this chesed is parallel to - yet again - the divine righteousness: "Your righteousness is like the mountains of God; Your judgments are like the great deep; man and beast You save, Yahweh" (36.6). David continues to celebrate God's chesed which brings refuge, abundance, delight, life and light (36.7-9), and again parallels chesed and divine righteousness in 36.10, beseeching Yahweh: "Draw [out] Your chesed to those who know You, and Your righteousness to the upright of heart."
Observations
Upon considering the sundry texts of Paul's great catena, I would like to make several observations in conclusion.
- Five out of the six texts from which Paul quotes are Davidic psalms. The universal context in these psalms has to do with the wicked persecuting the righteous. The righteous are invariably centered around David, the Lord's anointed. Given the Christ-centered reading we drew from Romans 3.1-8, this should not be surprising. The point at issue in Paul's charge against his contemporaries is that they have disbelieved the Anointed (= Messiah, Christ) and become guilty of His blood. We could put it thus: Israel has treated the Greater David, Yahweh's Servant, in the way that David himself treated Uriah, his faithful servant.
- The Christological aspect to Paul's use of these texts must be understood properly. For it would be incorrect to assume that "the righteous" simply is to be referred to Jesus, and that all others are "the wicked." The psalms, in particular, are not susceptible to a reading which simply places all imperfect men under wrath. They presuppose, and indeed articulate clearly, a juxtaposition of two real groups of people, the righteous and the wicked. And as we saw in the case of Psalm 140, "the righteous" are plural. We may say they are defined as such by their relationship to God and to David — but "David" is not the sole righteous one. If we are to take this context seriously, we must revisit the assumption that Paul's goal with the catena is simply to say everybody everywhere is only wicked. (In truth, we have no choice on that score; after all, as Paul continues to develop his argument, he will make clear throughout Romans that there is a people who is indeed righteous, not under Sin.)
- The righteousness of God is a constant among these texts. Only Psalm 14/53 does not mention divine righteousness in so many words. Psalm 9/10 speaks of Yahweh judging in righteousness, while the other passages speak directly of "Your righteousness" or "His righteousness." This righteousness is not an abstract revelation of "holiness." Rather, it is thoroughgoingly covenantal, along the lines of the Abrahamic promises: "I will bless those who bless you, and the one cursing you I will curse" (Gen 12.3); "I will be Your shield" (Gen 15.1). God's righteousness is therefore revealed to His afflicted people in the form of deliverance and salvation toward them, and vengeance upon their enemies, who are (by that very fact) also His enemies. Thus, the justice involved in "the righteousness of God" is not about punishment for imperfection; it centers upon faithfulness to God's covenantal self-description.
In my judgment, this conception of the divine righteousness is thoroughly decisive when it comes to determing the manner in which Paul is using the phrase "the righteousness of God" in Romans 3. It is scarcely conceivable that Paul quoted four passages speaking directly of divine righteousness (and a fifth which speaks of God judging in righteousness), and that his own references to divine righteousness carry a different meaning. Nor will it do to object that the precise phrase "the righteousness of God" does not appear in these texts. After all, as these are mostly psalms, they are marked by the second person appropriate to prayer ("Your righteousness"). And in any case, the Isaiah passage's use of "His righteousness" is identical to Paul's own "His righteousness" in Rom 3.26.
The necessary implication of this is that Paul's "righteousness of God" phraseology in Romans does not refer to a righteousness which God "imputes" to the believer. It refers to God's actions as a judge who is covenantally bound to save a people and to judge those who oppose them. It refers to God's faithfulness and truth (cf Rom 3.3, 4) in action.
Of course, this does not determine what Paul means elsewhere by the somewhat different phrase "righteousness from God." Nor does the phrase itself decide the issue of what sort of saving action God takes in demonstrating His righteousness, and I will say that I believe that in the event what God does is indeed something like what is generally called imputation. Later in the chapter, however, Paul does take us partway to understanding the nature of this saving action: the liberation in Christ Jesus involves His being set forth as a "propitiation by His blood" (3.25 ESV).
Romans 3:19–20
In our previous section, we examined the sundry texts from which Paul quotes in his great catena of quotations in Rom 3.10-18. But the thought unit is not yet complete; Paul makes his assessment of the implications in 3.19-20. This followup makes Paul's intent clearer, although it is frequently misread (verse 19, in particular; I think this is likely also the case with verse 20, but my understanding of the verse is still being formed).
Gentiles Under the Law?
Verse 19 offers this perspective on the catena: "Now we know that whatever the law says, to those in the law it speaks, so that every mouth may be closed and all the world may become guilty/liable to God."
Some misread this statement to mean that Paul thinks that "all the world" is "in the law." This, however, is not possible. In 2.12, Paul contrasts those who sin "in the law" (identical terminology to 3.19) to those who sin anomos ("apart from the law;" on the analogy of "in the law," the understanding is "outside the law"). The clear assumption on Paul's part is that Torah is for Israel, not for Gentiles, who are outside the law's polity.
When approaching 3.19, it must be recalled that Paul's imaginary interlocutor is a Jew. The assumption common to Paul and his ostensible argument partner is that Gentiles on the whole are subject to judgment; he does not need the catena in order to demonstrate that. Rather, Paul's concern has been to show (mostly from the Psalms) that there is no "king's X" exempting Israel from judgment.
Liability to Judgment
This is crucial to Paul's argument, because as we have seen, he has already demonstrated in 3.1–8 that Israel as a whole is guilty; but it has been his aim to show that this guilt is not simply to be overlooked. This is why the passages from which he quotes are so consonant with the sort of guilt he has established in the preceding passage: his kinsmen have sinned against God Himself by disbelieving His promises, rejecting His Messiah, and indeed, becoming guilty of His blood. And as it happens, the Psalms from which Paul quotes are all Davidic, and the wicked are defined over against him, just as the righteous are defined in relation to him. Thus we can infer a sort of "how much more" argument: If the wicked were those who opposed David — himself a sinner — and they were held responsible and judged on that account, how much more is it the case with those who oppose the Son of David, the promised Messiah Himself: they are liable for their guilt. (Actually, the "how much more" goes further, as we'll see in considering v 20a.)
"Liable" is thus likely the sense of hupodikos here, although not a lot rests on that, as Paul's point involves the guilt involved in the liability. While this is the only appearance in the Bible, BADG identifies liability or answerability as the normal meaning of the term, based on comparisons to Philo and Josephus — nonetheless, English translations of Romans 3.19 often render it "guilty."
Paul's Use of Psalm 143: Covenant Lawsuit
This brings us to verse 20, which at first glance appears to put things back into the framework of general lawbreaking: "Because from works of Torah no flesh shall be justified before Him, for through Torah is the knowledge of Sin."
The first part of verse 20 is a modified allusion to Psalm 143.2 (142.2 LXX). Paul's text reads, "from works of Torah no flesh shall be justified before Him." In the LXX, the verse as a whole reads, "And do not enter into judgment with Your servant, because no one living shall be justified before You." (The LXX sticks very close to the Hebrew in this case.) The latter part of this allusion is nearly identical, except that Paul has substituted "no one living" with "no flesh." This fits, not only with Paul's widespread use of flesh in Romans, but also with the connection he makes between flesh and death. Without contradicting the original intention of Psalm 143, Paul wants to say that in a real sense those who are in the flesh are not really living.
As for the rest of Paul's statement, he has substituted the idea of Yahweh entering into judgment with humans with his own theme phrase "works of Torah." (One question this raises is whether he is simply bringing Ps 143.2b into the context of his own discussion of works of Torah, or whether in fact works of Torah is in some sense intended to be epexegetical of Yahweh's entering into judgment with men. We'll leave this to one side, although it's fascinating and bears further investigation.) Men will not be justified from works of Torah before Yahweh.
More on that in a moment, but first let's backtrack.
Psalm 143, as it turns out, is yet another text which mentions (wait for it) the divine righteousness: "Hear my prayer, Yahweh, hearken to my supplications in Your steadfastness; answer in Your righteousness" (Ps 143.1; note also v 11: "For the sake of Your name, Yahweh, preserve me; in Your righteousness bring my soul out of distress"). By my count, that's now six of eight Old Testament texts referenced in this chapter so far which deal with the righteousness of God in the context. Still think that Paul's usage of the phrase is independent?
Amazingly enough, given how God's righteousness is frequently spoken of, the pleas of Psalm 143.1 and 2 contrast two scenarios: one in which Yahweh answers according to His righteousness, and one in which He enters into judgment with His servant. And yet, in association with this latter case, David says that before Yahweh no one living is righteous.
What we find, then, is that the tendency to associate divine judgment with a perfect standard is not utterly wrong. David himself confesses that if Yahweh enters into judgment with anyone, that person is ruined, for before Yahweh, no one living is righteous.
But how can we fit these two sides of the story together?
Let's start by recognizing what is widely overlooked regarding the nature of judgment in biblical terms. Note what "entering into judgment" entails. It does not simply mean that God is sitting as an impartial judge. To "enter into judgment" with someone means to take opposing sides in a case: prosecutor and accused.
Thus it is not at all inconsistent of David to appeal to Yahweh, "Judge me according to Your righteousness" — or even, "judge me according to my righteousness" (Ps 7.8) when he is seeking aid over against his enemies and his afflictions. Because David knows that Yahweh has covenanted Himself to His people, and He judges in their favour. But it is an utterly different story if God makes a covenant lawsuit against His own people; then there is no longer a mediary to whom to appeal (cf 1 Sam 2.25). All disputes involve at least one unrighteous party; in any dispute between Yahweh and men, it is certain that no man living can possibly be righteous. (For a biblical instance of a "covenant lawsuit" between Yahweh and His people, see e.g. Micah 6.1–5.)
For whatever reason, then, Paul places "from works of Torah" in place of "entering into judgment." Whatever that reason is, one thing is clear: the scenario which he is addressing has man in contention — legal dispute — with God Himself. And Paul says that if Yahweh has entered into dispute with men, being an observant Jew isn't going to cut it.
This again comports well with our reading of 3.1–8: Israel has quite literally entered into judgment with Yahweh by prosecuting the Messiah, who in fact is Himself Yahweh. Again, no amount of devotion to works of Torah is going to save them in such a contention.
The second part of 3.20, intended in some way to ground the statement of 3.20a ("for"), sounds somewhat like chapter 7, where Paul says that the law became an occasion of sin for the flesh — like the commandment itself became a temptation ("rules are made to be broken").
The frequent understanding of the statement in 20b is that the law identifies sins — yet, even given the factors of chapter 7, it's hard to think that understanding the argument in that fashion does not produce a non sequitur.
But there is a further problem: Paul does not say that through the law is the knowledge of sins (plural), but sin (singular). This is why I have capitalized Sin in my translation above. As we progress through Romans, we find that Sin is not simply an abstraction of individual misdeeds (although it certainly is reflected in such misdeeds); it is a power which rules over all men in Adam (e.g. 5.12), a power broken only by union with Christ who conquered it in His death (6.6ff).
"Knowledge" here probably doesn't simply refer to an intellectual apprehension of something; Paul seems to be using the term in the more full-orbed biblical sense that entails experiencing something from the inside out. The fullest experience of Sin, the power, is discovered within the context of Torah. This is true, in part, because it specifies commandments and prohibitions, just as the tree was specifically prohibited to Adam. Thus one's experience under the law involves awareness that is not the case outside of it.
However, there still seems to be more involved than that. Paul writes, not merely that Torah identifies sins, as we've mentioned; he says that "the law came in to increase the trespass, but where Sin increased, grace abounded all the more" (5.20). Sin comes to be "accounted" in the context of Torah (5.13), to the effect that Torah brings wrath, while where there is no Torah there is no transgression (4.15).
Verse 5.20b is likely a summary statement of what Paul says later, then. The statements of chapter 7 are certainly related to this, but if anything, this verse is closer to the more foundational thoughts in chapter 5, particularly 5.20: the law entered in order to increase the trespass.
Whatever else we may say regarding 3.20b (and 5.20 etc), one thing should be clear. Being under Torah — indeed, being devoted to Torah's works — is not itself the deliverance of Israel. Rather, in some way Torah has provoked Israel's rebellion to the degree that she has disbelieved and entered into judgment against her Messiah and her God — all in the name of the law itself. This reveals the extent of Israel's trouble. She is under Sin, and under judgment; she has entered into a court dispute with Yahweh Himself, where no flesh will be justified.