Jesus the Jewish Prophet

Jesus certainly did not intend to found a new religion.

He did not repudiate Scripture, though on occasion he emphasized some Scriptural principles at the expense of others. With a few rare exceptions he did not call in question the law of Moses. But he did challenge established conventions and priorities.

Jesus believed he had been sent by God as a prophet to declare authoritatively the will of God for his people: acceptance or rejection of him and his message was equivalent to acceptance or rejection of God. Graham Stanton, The Gospels and Jesus pp.269-270, Oxford University Press, 2002
Stanton (1940–2009) was Lady Margaret's Professor of Divinity at Cambridge University

Judaism was more than a standard challenge to Christian identity; it was also a competitor for Gentile adherents.

During this period [1st and 2nd centuries] and long after, Gentiles continued to attach themselves to the synagogue for the same reasons that had always drawn them before: Judaism's monotheism, its antiquity, its articulated ethics and strong community, its claims to revelation, and its prestigious sacred text.

The rise of the Gentile Christianity is itself the best evidence of Judaism's appeal: the church, though it repudiated the synagogue, also used it socially and religiously as a model.

Christianity thereby offered to Gentiles fewer of Judaism's disadvantages (circumcision for adult males; association with a nationality implicated, after the bloody revolts of 66, 117, and 132, in anti-Roman activity) but many of the same attractions (strong community, revealed ethical guidelines, and the scriptures themselves – already available, thanks to the Hellenistic synagogue, in Greek).

But the churches competed for these Gentiles against a religious community both better established and more broadly recognised. Here Christianity again offers the best evidence of Judaism's abiding appeal.

Christian invective, from the gospels through the writings of the second-century fathers and beyond, most often and most energetically targeted Judaism. Why? If its goal were to wrest Gentiles from the errors of paganism, one would expect more attention to polemics against idolatry; if its goal were to condemn the unethical exercise of power, one would expect stronger criticism of the empire, which after all had executed the Saviour and continued, sporadically, to persecute his followers.

Why expend so much effort disparaging a community ostensibly engaged in compatible activity, turning Gentiles from idolatry to the worship of the God revealed in scripture? Because, to those Gentiles drawn to such religions and such communities, Judaism represented an attractive alternative to the church. Paula Fredriksen, Jesus to Christ: The Origins of the New Testament Images of Jesus pp 211-212