This is the verse that will mess with your paradigm. One verse, and it basically vindicates the heart of what we used to call the "New Perspective On Paul": A good first century Jew was no sort of legalist. To the text! I'm going to include verse 16, and comment on other verses, as well:
"We ourselves, who are Jews by birth and not Gentile sinners, 16 yet who know that a man is not justified[a] by works of the law[b] but through faith in Jesus Christ, even we have believed in Christ Jesus, in order to be justified by faith in Christ, and not by works of the law, because by works of the law shall no one be justified." (Gal. 2:15-16, RSV)
He's talking to his fellow Jews here, and he's synthesizing what he knows from the Old Testament with what Christ gave him. Jesus must have believed it was graciously possible for anyone who read or heard the Scriptures up to that point to receive Him; otherwise, why come at all? To say nothing of his frustration at the lack of faith he finds. And here's the big key: Most of Jesus' audience, and most of St. Paul's, is Jewish. So, when he says, "works of the Law," we've got to read that how they would have read it: as referring to the ceremonies with which they were all familiar. What exactly is wrong with Jesus' opponents in the New Testament? Not that they followed rules, but that they understood their faith and redemptive history in such a way as to reject Jesus. And this has a practical application, friends: Rules without the gracious context of redemption are empty and useless. Remember what St. John told us in his Gospel: "He came to his own, but his own did not receive him." We've got to be clear on this very point: The Pharisees and others didn't simply reject Jesus and His New Covenant; they twisted the Old one, also. That twisting has a legalistic thrust, to be sure, because outside of God's grace, legalism will be all you have.
What implication does this have for Romans 3? A huge one. Frankly, Luther had no idea what the text really said. Your key verse there is Romans 3:29. Read that about 5 times, and realize that he's saying the same thing he's saying here: Salvation is not just for the Jews! It never really was. And this means that we've got to have the New Testament faith/works discussion in the real context of the New Testament, not in that of Luther's prejudice and theological reductionism. N.T. Wright may not like the implications of his work, but the truth is, the Protestant Reformation was built on Luther's prejudice and theological reductionism. Clearing that away is bound to have ecclesial implications.