Why do Roman Catholics regard St. Peter as the first pope?

Roman Catholics regard St. Peter as the first pope based on the Petrine theory, a theological principle asserting that Jesus Christ designated Peter as the leader of the church and his representative on earth.12

This belief is primarily grounded in specific biblical passages where Jesus confers unique authority upon Peter:

• The "Rock" and the "Keys": In Matthew 16:18–19, Jesus tells Peter, "You are Peter, and on this rock I will build my church," and promises him "the keys to the kingdom of heaven," granting him the power to bind and loose on earth and in heaven.13
• The Pastoral Commission: In John 21:15–16, Jesus instructs Peter to "Feed my lambs" and "Tend my sheep," which is interpreted as a mandate of leadership over the faithful.3

According to Roman Catholic teaching, this authority was not limited to Peter but was passed on in perpetuity to his successors as the bishops of Rome. This doctrine of apostolic succession establishes the papacy as a continuous line of authority, positioning the pope as the successor to the prince of the Apostles.132