Final answer:
St. Paul, after a dramatic conversion experience, became an essential figure in the spread of Christianity by preaching about Jesus to both Jews and Gentiles, and emphasizing universal salvation through Christ. He traveled widely, wrote influential epistles, and played a key role in broadening Christian membership beyond Jewish communities.
Step-by-step explanation:
St. Paul, formerly known as Saul, had a profound conversion to Christianity on his way to Damascus, as narrated in Acts of the Apostles. An experience so transformative that it led him to become one of the most influential figures in the spread of Christianity. After being struck blind and subsequently healed through the intercession of Ananias, Paul began preaching about Jesus with renewed fervor. He articulated the doctrine that Jesus's death on the cross was a divine plan to erase human sin and preached not only to Jews but also to Gentiles, affirming the potential universality of Christian salvation.
During his missions, Paul traveled extensively through the Greco-Roman world, to cities like Ephesus, Corinth, Thessalonica, and Rome, confronting the diverse religious and cultural experiences of these regions. His epistles to the communities there formed a crucial part of the New Testament and laid the foundation for the development of Christian doctrine. His preaching often centered on the belief in a single, all-powerful God's love, Jesus as the Son of God, and the promise of eternal life after death, which was especially appealing to marginalized groups in the Roman Empire, like slaves.
Paul's influence was pivotal for the church's decision that Christianity and its salvation were available to everyone, not just Jews. This significant expansion of the faith's reach was a major factor in the growth and eventual dominance of Christianity in the late Roman Empire and beyond.