Why do Catholics think St. Peter was the first pope?
Catholics believe that St. Peter was the first pope largely on the words of Jesus in Matthew 16: 18-19. There Jesus appears to set Peter above all the other apostles. He appears to make Peter the head of the church. In this passage, Jesus calls Peter the rock upon which he will build his church. He goes on to say that Peter will get the keys to the kingdom of heaven and that whatever decisions he makes on Earth will be accepted in heaven as well. The Catholic Church argues that this shows that Jesus was giving Peter precedence over the other apostles and making him leader of the church. Therefore, he was the first pope.