6 Paul the Apostle of Tarsus c. 5–c. A.D. 67 : Paul is quite possibly more responsible for the dissemination of Christianity, its ideals, theology, and principles, than anyone else. He is venerated in all branches, as a saint in many, or at least as a profoundly respected teacher, preacher, and the chief Christian apologist. And he did all this via 13 letters to various churches and people throughout Asia Minor.
He was the first person to write anything that was later canonized into what we call the New Testament. He probably wrote his first epistle, to the churches in Galatia, in about A.D. 50, give or take 5 years. Mark wrote his Gospel 5 to 10 years later. Paul’s theological thesis throughout his 13 or so Epistles is a more detailed statement of Jesus’s philosophy of ethics and salvation given in the Gospels. Paul’s central point is that all you have to do is believe that Jesus is the Son of God, Savior of the world, rose again from the dead and ascended into Heaven, and you will not die. Your transition may be painful, but you’ll go to Heaven.