The literature on the New Perspective on Paul is vast, to say the least. There are volumes supporting and extending Sanders’ work, there are others critiquing his work. Some are aimed at N. T. Wright as a particularly popular proponent of the New Perspective, others championing the classic Reformation view with a zeal worthy of Elijah. This is far from a complete list of responses to the New Perspective, please feel free to suggest others in the comments.
Among the most valuable responses is the collected essays in Carson, O’Brien, and Seifrid, Justification and Variegated Nomism: Volume 1 – The Complexities of Second Temple Judaism (Tübingen: Mohr Siebeck; Grand Rapids, Mich.: Baker, 2001); Volume 2: The Paradoxes of Paul (Tübingen: Mohr Siebeck; Grand Rapids, Mich: Baker, 2004). This material covers the same material as Sanders (and even more). Each chapter takes a section of the literature and evaluates Sanders’ “covenantal nomism” in the light of that literature. In most cases, there is something which can be used as support for Sanders’ view of Second Temple period Judaism, but the evidence is far from uniform. Some Jewish writers may have thought of election and boundary markers as Sanders described, but others did not. The situation is far more varied than Sanders allowed for in his Paul and Palestinian Judaism.
Mark Seifrid has been a strong voice in favor of a more or less traditional view of Paul. His Christ, Our Righteousness: Paul’s Theology of Justification (Downers Grove: Intervarsity, 2000) is a brief treatment of the topic but among the very best and most accessible for the layman. Seyoon Kim engages James Dunn in his Paul and the New Perspective: Second Thoughts on the Origin of Paul’s Gospel (Grand Rapids, Mich.: Eerdmans, 2002). Stephen Westerholm’s Perspectives New and Old on Paul (Grand Rapids, Mich.: Eerdmans, 2004) surveys Augustine, Luther, Calvin and Wesley as well as the “Lutheran” interpreters of Paul in the twentieth century before turning to Paul’s view of the Law and Justification in the final third of the book. This historical approach seems backwards to me, but it really does “work” in practice. Francis Watson recently revised his Paul, Judaism and the Gentiles (Grand Rapids, Mich.: Eerdmans, 2007), attempting to break through the false dichotomy between either the Traditional “Lutheran” view and the New Perspective. In many ways, Watson’s work draws the best from both views of Paul and attempts to build a biblical theology of Paul.
While studies challenging Sander’s position are not unique, they are almost always from the Calvinist side of the Reformation and are intent on defending the reformation view of justification by faith in Paul. Chris Vanlandingham has charted a new course in that he approaches Sanders from a decidedly Arminian view of salvation and the last judgment. For Vanlandingham, Sanders is guilty of the very sins of which he accused scholarship in his Paul and Palestinian Judaism – he reads the Reformation view of grace and works back into the literature of the Second Temple period and finds a robust view of election. Vanlandingham contends that Jewish literature of this period uniformly describe the final judgment as a judgment by works, including the Apostle Paul. (Chris Vanlandingham, Judgment And Justification in Early Judaism and the Apostle Paul. Peabody, Mass.: Hendrickson, 2006.)
Paul Rainbow wrote a biblical, theological and historical reassessment of the classic Reformation reading of Paul’s teaching on Justification. In their zeal for sola fide, Rainbow argues the Reformers have obscured obedience as a required element of the Pauline doctrine of justification. By sharply separating justification and sanctification in the slogan sola fide, the Reformers not only violate the rule of scripture, but therefore have no real antidote for antinomianism nor any encouragement for Christian obedience. Rainbow therefore argues for a “round view” of justification which emphasizes the dynamic tension present in Paul’s theology. Rainbow therefore advocates a form of synergism, a twofold justification which attempts to balance justification by faith apart from “works of law” with a future justification by “good works” when the believer stands at the final judgment. This double-justification is analogous to the two-stage kingdom of God: we are already justified, yet we are not yet justified (224-225). (Paul A. Rainbow, The Way of Salvation: The Role of Christian Obedience in Justification. Paternoster, 2005).
Another dozen titles could be added to this list if I included responses from systematic theology, but these are among the best which i have read on the New Perspective and are all worth reading to balance the more polemical books out there.