I used to share H. G. Wells's disdain for Paul as a popularizer rather than a visionary. But now I admire him as a popularizer. Specifically, Paul took Jesus' ministry, which was by and for Jews, and spread it to the whole world. He saw the universal potential of a God who is Love.
Other than Paul's churches, the early Christian churches were predominantly Jewish. Gentiles had to convert to Judaism to join the community of Jesus' followers. Jesus' family led the movement from Jerusalem. Paul, however, went for the gentiles, and he got them. And it's the resulting religion of universal love that eventually did away with slavery, established human rights, etc.
Paul as Satan's Dupe: A less kindly depiction of the apostle to the gentiles.