Who is the Christian of whom Rosner speaks?
Perhaps this will appear to you to be a quite unusual question at first. Of course Christians are followers of Jesus Christ both Jew and Gentile you might say. This certainly seems to be the way Rosner is using the term. He states in the conclusion: “although Jews are under the law, believers in Christ are not” (p. 418). This understanding of identity in Paul however is anachronistic and false. It is true that in one place Paul distinguishes Jew, Gentile and the ekklesia of God (1 Cor 10:32). But this type of categorization is exceptional and whatever it might mean, it does not denote the so-called “third race” theology prevalent in the some circles today. Paul’s categories for identity are binary sets: Jew and Greek, male and female, and slave and free (Gal 3:28). For the sake of argument, even if the term "church" were taken as a category for Paul alongside the ethnic distinctions, the term "Christian" was not.
Rosner’s study exhibits this common category error and consequently the thinking does not reflect the complexity of the issue adequately. The result of this weakness is that his conclusion that “a major shift in the way the people of God relate to the law” has occurred for Paul cannot be sustained. While it may be true, the argument in this essay is too weak to establish it.
Let me put my point in a simple a question: Was a Jewish believer in Jesus at the time of Paul a Jew or a Christian?