St.Paul is the greatest convert and the greatest missionary that God has ever given to His Church.
Saul of Tarsus was a well-educated and zealous young rabbi, very determined that nothing should change or dilute the Jewish religion. He was committed to searching out and punishing members of what was (to him) an unacceptable new sect within Judaism, those who followed Jesus of Nazareth. For Saul, their revolutionary new religious faith was a blasphemous lie; they claimed that their crucified and risen Master was the Son of God.
Saul was called into Christ’s service through a vision of Him on his way to Damascus. That meeting with the risen Lord was the turning point in Saul’s life. He was converted to faith in Christ, and became Paul. Christ became the entire raison d’etre of his new faith and his new vocation. He wrote “It is not I who live, but Christ Who lives in me” (Gal.2:19-21). The one who had been uncompromising in his persecution of Christians discovered that his true calling was to take the truth of Christ to the Gentiles.
Paul’s Damascus road conversion experience matured into a profound and dynamic love for Christ. That love speaks eloquently in every New Testament letter written by Paul. His urgent love bore fruit in his heroic missionary work of evangelization, a mission based on his new faith in Christ’s divinity and His unique role as Messiah and Saviour.
Paul knew that the truth about Christ which had been revealed to him was new and definitive. The heroic convert did not indulge in mind-games by pretending that his new faith was not different. Paul knew that Jesus of Nazareth was Messiah, the Redeemer whose death and resurrection changed the world for ever. Paul knew that in Christ the new and everlasting covenant had finally been established, once and for all. In that new and final covenant all God’s earlier promises were fulfilled. Paul knew that God’s final and greatest covenant with His People would never be revoked or superseded.
For a correct understanding of the Church’s teaching about Judaism and Christianity we can do no better than to imbibe that teaching at its pure and revelatory source – the inspired Word of God in the New Testament of the Holy Bible. The four gospels together with St.Paul’s own letters and the epistle to the Hebrews reveal the truth of the matter with unambiguous clarity. There we have the revealed truth, plain for all to read.
The 1992 Catechism of the Catholic Church gives authoritative elucidation of this and all other truths of Catholic faith and morals.
http://www.vatican.va/archive/ENG0015/_INDEX.HTM