Which of the following was a major effect of Paul's conversion to Christianity?

Paul, after Christ's death, became one of the main reasons that the Roman empire converted to Christianity. He went on many long trips deep into the empire, preaching and spreading the religion. He and the other disciples affected so many people, that the Roman emperor Constantine made it legal to practice other religion in the empire. Eventually, because Paul started a chain reaction, and the emperor after Constantine, Theodosius, made the empire's main religion Christianity.

Paul, after Christs death.