The new perspective on Paul (NPP) is first and foremost about Paul's Jewishness. To separate him from this deeply rooted identity is to misunderstand Paul, and therefore most of the New Testament. Interpretation of key doctrines like justification are significantly impacted by this re-reading of Paul through a first century Palestinian Jewish lens. Paul lived and died a Jew - a Jew who believed that Jesus was indeed the messiah, but he did not think of himself as launching a new religion but rather continuing on in Judaism as writers like Eisenbaum, NT Wright, Marcus Borg, JD Crossan, Scot McKnight, Bart Ehrman, and EP Sanders have all made the case for. It should be obvious that though these authors all belong in the NPP camp, that doesn't mean they all agree. The NPP provides a new foundation to jump off of for all of these scholars, but they still end up in different places.
For Eisenbaum, Paul is ethnically, culturally, religiously, morally, and theologically Jewish and she wants to encourage both Jews and Christians to embrace Paul under a different light. For the former, he is not the anti-Jewish heretic some have made him out to be, and for the latter he is not the idealized Christian convert who started Christianity. To take Paul's Judaism seriously is more than just paying lip-service to this fact (a clear criticism of her NPP contemporaries) and it means putting him in the context of a Hellenistic Jew from the Greco-Roman era who speaks Greek and is influenced by Greek thought and culture. Putting Paul in this context will show that the long history of Christian anti-Judaism based on poor interpretations of Paul's letters and missionary work is misguided. She makes the claim that the Pharisaic Judaism that Paul comes from would have been very familiar with Paul's claims - a belief in a messianic savior figure and the general resurrection of the dead are very Jewish ideas and not so heretical.
Eisenbaum's study of Paul relies on the seven undisputed letters of Paul, rejecting 1/2 Timothy, Titus (the pastorals), Ephesians, Colossians, and 2 Thessalonians on the basis of internal and external evidence showing them to be almost certainly the products of later Christians writing pseudonymously in Paul's name. This is common amongst New Testament scholars today and the evidence is quite convincing. Acts is also viewed as historically problematic as there are multiple contradictions between it and Paul's own accounts of his journey's - this is also the view of the majority of NT scholars today. There are interpretive ambiguities she highlights and what look like contradictions within the same undisputed letters that highlight the need for more sensitivity to Paul's context.
That's a quick introduction to the book that takes us through a summary of the first couple chapters. More to come.