There are a few battleground ideas and texts on which the New Perspective differs from the traditional view. First and foremost is the nature of Judaism in the first century. From the traditional perspective, Judaism was a legalistic religion which required works for salvation. This was often stated but rarely proven, especially in popular presentations. The Pharisees are described as hand-wringing legalists who sought to burden others with onerous laws which made little sense. Perhaps there is an undercurrent of anti-Semitism here, but more often than not this mischaracterization is simply the result of ignorance of what Jews actually believed in the Second Temple period.
Israel’s election is confirmed by God’s gift of the Law and his requirement of obedience to that law. Everything we know about Judaism in the Second Temple Period is predicated on the fact that God gave the law and he required his people to obey. Because Israel is chosen and given a Law and the responsibility of obedience, she is liable for both rewards and punishment; to experience both God’s justice and mercy. God cannot let an evil-doer escape. He is all-knowing and punishment is certain (Antiq. 1.14; 3.321, 4.286).
Perhaps the most controversial point in Sanders’ view of common Jewish theology is that Judaism was a religion of grace. As noted above, the Christians often describe Judaism as a works-salvation in contrast to Paul’s salvation by grace alone. Everything in Jewish religion seems to point to the grace of God in this life. Whatever one has, whatever one is, it is only by the grace of God. One did not do the various “works of righteousness” (circumcision, food traditions, but also shema, prayer, wearing tefillin, etc.) in order to receive grace; rather one did them in response to the grace already received.
If this is a correct understanding of Judaism, then it seems to me that it is rather a” Pauline” way of expressing ethical obligations. Or maybe Paul is rather still Jewish in his ethical teaching! Paul never says one can be right with God on the basis of good works, it is only by God’s sovereign choice to adopt the believer as a member of his family that we can be saved: by grace through faith. But it is well know that Paul also gives many ethical and moral commands which he expects from his churches. These are not requirements to be saved, but the natural response of those who are “in Christ.”
To summarize this point for Sanders: Election is what placed the Jews “into” the covenant; obedience is what “keeps them in.” There are a number of mechanisms which are used to deal with disobedience, all of which are expressions of God’s grace. There is nothing Israel did to merit this election. Israel is given every help possible by God’s grace to assist them in the “keeping in” element.
On the whole, I think Sanders is correct that Judaism in the first century was a religion of grace, but there was also a strong attraction to legalism among both Jews and Gentile converts to Judaism (and later, Christianity). A major cornerstone of the theology of the Hebrew Bible is the gracious loving-kindness of God, his hesed. Nowhere in the Hebrew Bible do we read of someone who claims to be burdened down by the impossibly heavy load the Law. Rather, keeping the law is the proper response to a gracious God. The big difference between Paul and Second Temple Judaism is his view of Gentiles keeping the Law.