It is commonly, but perhaps unfairly said:
“But without Paul, Christianity would have remained a Jewish backwater, never to become the world religion it is today.”
There is no way we can second-guess history, but if we theoretically remove Paul from early Christianity, we are still left with a very interesting situation.
Before Paul started his mission, there were already non-Jewish converts to the Jesus movement. Some were probably “spontaneous” converts who may have chanced to hear Jesus’ own teaching, or the apostles’ preaching. Others may have converted by dialoguing with members of the “Hellenist” Jewish Christian party which was expelled from Jerusalem after Stephen’s martyrdom. In any case, it is clear that not all non-Jewish converts were “brought in” by Paul.
It is to these non-Jews that Jesus’ brother James – head of the church – compassionately and pragmatically extended the hand of brotherhood.
James decided that non-Jewish converts could simply follow the handful of simple rules contained in the Noahide Covenant – the covenant which, Jews maintained, Yahweh had made with all humankind, long before the Abrahamic-Mosaic covenant was established. James’ decree freed gentile converts from kosher, obedience to the Mosaic Law, and circumcision. Thus, James had, early on, planted a perfect gateway for gentiles to enter the Jesus movement without first “becoming Jews”.
So already we see that the Jesus movement was priorly designed to accept Gentiles by way of a very simple rule. It is entirely possible that this small but colossally important step would, of itself, have successfully planted seeds of its own in the Empire, quite apart from Paul’s missionary activity. From Paul’s own letters, we know that there were many missionaries in the extra-Judean, Greco-Roman world. We even know that sometimes Paul would send letters to churches that he himself had not founded. That is, Paul did not found every extra-Judean church, nor were all the other missionaries necessarily “Pauline”.
Therefore, the idea of a Gentile, Greco-Roman Christianity without Paul, is not, on the face of it, at all absurd.
In fact, depending on its reception among Hellenistic synagogues, the original Jewish-sectarian form of the Jesus movement may have burgeoned into a new branch of Judaism: a form of Judaism that followed Jesus’ Torah-interpretation, his teachings about the here-and-now presence of God’s Kingdom on earth, his parables, his poverty ethic, etc. After all, this was already being done in Jerusalem, the chief opposition being only the priesthood. In the extra-Judean Empire, distanced from the priesthood, perhaps the movement would have flourished in ways it could never have in the land of its origin.
Perhaps, then, the concept of a large Jewish Jesus-movement, successful and influential in the wider Empire, without Paul, ought not to be lightly dismissed. It may not have ultimately amounted to a “world religion”, but it could have had the potential of being a strongly influential branch of Judaism which, refracted through the character and teachings of Jesus, welcomed both Jews and non-Jews to a common table within the fulfilled Jewish promise of a heavenly kingdom functioning on earth.