Final answer:
St. Paul was important to the Catholic Church because he spread Christianity, provided theological insights, and helped solidify the authority of the Pope.
Step-by-step explanation:
St. Paul was important to the Catholic Church for several reasons. First, he played a major role in spreading Christianity to the Greek and Roman cities of the ancient Mediterranean world, such as Ephesus, Corinth, Thessalonica, and Rome. This helped Christianity to become more widespread and established. Second, St. Paul's teachings and writings, which are included in the New Testament, provided important theological insights that shaped the beliefs and practices of the Catholic Church. Finally, St. Paul's conversion and his work in the early Christian communities helped to solidify the authority of the bishop of Rome, who eventually became known as the Pope and played a significant role in guiding and leading the Catholic Church.