Did early christianity succeed because of Jewish conversions?

Responding to Rodney Stark's recent work on societal factors leading to the success of early Christianity, the author challenges Stark's finding of a majority Jewish component in early Christianity. First, Sanders argues that Hellenized Jews in the Roman period were not comparable to assimilationist Jews in the 19th and 20th centuries: most in reality remained firmly oriented to their religious culture. Second he questions Stark's proposal that Christianity took root in those cities where there was already a sizable Jewish population, on the grounds that Jews were everywhere around the Mediterranean, so that prior Jewish presence loses all significance. An examination of the surviving evidence shows that, while a Jewish-Christian presence can be identified in some locations, in fact most people who became Christians in the early years were non-Jews.