This forced the followers of Jesus to make a decision. Were they going to continue to be Jews following stricter laws set forth by rabbis, or were they going to be something else? The decision to open up their religion to non-Jews, people who weren't part of the covenant, is the central reason that Christianity could become a world religion instead of just a sect of Judaism. And it probably didn't hurt that the main proponent of sticking with Judaism was James, Jesus' brother, who was killed by the Romans. Reason number two is related to reason number one, and it's all about a dude named Saul. No, not that Saul. Yes, Saul of Tarsus, thank you.