Paul the Apostle spread the news of Christianity throughout the Roman Empire. The numerous letters that he wrote to churches around the Mediterranean Sea include theological ruminations and explanations that were important to shaping Christianity as an institutional religion.
The letters that Paul wrote eventually became part of the New Testament of the Christian Bible. One important aspect of Paul's missionary work and his writings was his understanding of how to apply Christianity in a non-Jewish context. As a Roman citizen who was also Jewish, Paul knew how to talk to both Jews and non-Jews, and his writings take advantage of this knowledge to make a broadly appealing message.