Scot McKnight summarizes James D. G. Dunn’s concise, albeit heartbreaking, explanation of why the term “Jewish Christianity” is redundant—and why many Christians have forgotten that fact:
There is something of an oddity about the title ‘Jewish Christianity’. For in a very important sense, that is what Christianity is — at least in its beginnings, and integrally in its character. In an important sense, often lost to view, the adjective ‘Jewish’ is quite unnecessary, since Christianity, with a Jewish Messiah as its central figure, and its holy scripture predominantly written by Jews, can hardly be anything other than ‘Jewish’ in a crucially defining sense. The oddity, rather, at least arguably, is that Christianity so quickly lost sight of its Jewish roots and character, that ‘Jewish Christianity’ became just one form of Christianity, almost a primitive form to be lost increasingly to view as Christianity became more international and less definitively Jewish in character. The increasing loss of distinctively Jewish identity is one of the most striking features of the first two centuries of Christianity. The growth of a contradictory adversus Iudaeos tradition which came to dominate Christianity more or less up to the present day has a self-contradictory character. To reckon seriously with this fact is still one of the great challenges facing twenty-first-century Christians, when the memory of the Holocaust is still unspeakably raw.