Flobadob, unless you, like Chakka, believe that Jesus didn't exist, it isn't really a theory, but we can only examine and try to piece together the information we have before us. St Paul began life as Saul of Tarsus. To put it simply, he persecuted what we call the early Christians (they weren't Christians - they were Jews) and then one day he was temporarily blinded by a vision of the resurrected Jesus. He then determined to 'spread the word' (even though he had never heard 'the word' - well at least since he never met Jesus he'd never heard it from the horse's mouth, so to speak). He argued with Jesus' followers who, like Jesus, were Jews, and who it appears, again like Jesus, had no intention of founding a new religion. They, unlike Saul - aka Paul - insisted that Jewish law be adhered to and that Jesus' message was for the Jews alone. (Jesus, incidentally, instructed his followers to keep Jewish law). Paul subsequently took his own message to the Gentiles (non-Jews), abandoning in the process, and for the specific purpose of influencing the Gentiles, many of the Jewish laws including those relating to diet and to circumcision. That was the foundation of the Christian religion we know today.
continued...