Barrie Wilson contends in his book How Jesus Became Christian that first century Palestinian Jews were deeply focused on the "problem" of Hellenization, which he characterizes as various threats to the purity of the Jewish faith at that time from outside influences (specifically Greek.)
This presents an image of a Judaism that had to be on constant guard lest its theology or practices, handed down directly from God to Moses, be altered somehow. One might refer to this as the "Barbarians at the Gates" theory of Judaism. (Ironic, since it was the Greeks who coined the term "barbarian" to describe anyone but themselves.)
Never mind that the Torah was not actually handed directly from God to Moses, but was the redacted product of multiple layers of authorship over many years, produced by various competing factions with different theological and political agendas. The more interesting question, I think, is that Wilson focuses on Hellenization but ignores the problem of Zoroastrianization.
Consider this. Judaism was influenced by Zoroastrianism after the time of the Babylonian exile, which meant that first century Judaism was different from what it might have been, thanks to the pernicious influence of that other religion. In this case, Zoroastrianism handed to Judaism the idea of life after death. By Jesus's time, most Jewish parties (besides the Sadduccees) had come to believe in an afterlife--and thus the Jewish faith had already been largely polluted by Zoroastrianization. As Uta Ranke-Heinemann points out in her book Putting Away Childish Things,
Long before the age of Maccabees, belief in life after death had penetrated the conciousness of the Greeks--in Plato, in Stoicism, in the mystery religions, and in popular beliefs. But for the Jews, a still more important influence than Greek ideas of immortality seems to have been the Persian belief in the resurrection. The Jews had been in extremely close contact with the Persians, because from 539 to 333 B.C. the found themselves under Persian sovereignty. (p. 232)It gets worse. By the time of Jesus, some Jews, such as the Essenes, had refined this belief even further to reflect the influence of--you guessed it, the Greeks. Whoa, Nelly, can it be true? Ranke-Heinemann writes,
The Greek doctrine of immortality changed the thinking of some Jews. Now they believed that souls of the just no longer went, even temporarily, like Abraham and Lazarus, into the kingdom of the dead. Instead they went off immediately to the heights of heaven. That was the view of the Essenes, who are nowadays more or less identified with the community at Qumran. (p. 235)Josephus, who described this belief in some detail, also described his own beliefs, which were similar.
Ranke-Heinemann adds that the evolution of ideas about the afterlife was continuing on through the first century, to the point where Sheol as even some sort of halfway house for the dead faded away, at least as far as righteous people was concerned.
It seems to me that there might be a lesson here somewhere. The idea that first century Jews would never have modified their faith as the result of external influences--a key premise in Wilson's conspiracy theory about Jesus and Paul--just doesn't hold water. Theology never stands still, does it? New ideas, even ideas from other religions or cultures, can influence the course of theological development. This happened during the course of Jewish religious history. Even before Zoroastrianism, the experience of the Exile itself deeply influenced the Jewish understanding of God's relationship with the Jewish people. Time doesn't stand still, and neither do religious faiths.