It's pretty safe to say that the Apostle Paul's influence on the Christian Faith is more significant than any of the other Apostle's (I'd argue that it's even more significant than Jesus himself), so the question becomes: what if Paul the Apostle stays Saul of Tarsus? What shape does Christianity take? Does it even get off the ground as a major religion, or does it stay a minor cult? What affect does this have on the rest of the world (or the Roman Empire, at the very least)?