What was the most important factor in the success of Christianity?

The evolution of Christianity is fascinatingly unique, for it started as a persecuted sect of Judaism and became the official religion of the Roman Empire. The appealing nature of the religion, and the actions of the Roman emperors such as Constantine and Theodosius were factors that helped spread Christianity throughout Europe, though St. Paul was the key to Christianity becoming a successful religion.
Paul, who started out as a Christian persecutor, was struck down by God making him a strong believer in the Christian faith. Paul then takes on the mission of spreading Christ’s message to all nations. He travels across the Roman Empire, Asia Minor and Greece preaching his message. Paul saw that Christ’s message focused on moral and ethical values and did not follow the Jewish laws and rituals. Paul believed that Christianity was universal for all people. He preached to gentile audiences for he did not see the need to be Jewish in order to follow Christ’s teachings. This decision is what allows Christianity to become its own universal religion, and essentially allowed it to grow and flourish. By making Christianity independent Paul allowed for many other European groups to become interested in this religion. Without the numerous non-Jews Christianity would not have had enough followers to survive.
Once Christianity was a separate religion they were able to make progress with their rights. In 313 C.E. Constantine gave Christians the same privileges as other religions with the Edict of Milan. Emperor Theodosius followed by making Christianity the official religion of the Roman Empire. Though these two men were very important to the great accomplishment of Christianity becoming a dominate religion, Paul was the one who saved Christianity by opening it up to all and spreading it with his missionary journeys.