After training the disciples and Apostles to form the organisation of His Church, Christ chose Simon Peter and made him the leader. Simon, whose name Christ changed to Peter, was the Head of the Church. Christ promised to build His Church on Peter, saying: “Thou art Peter, and upon this rock I will build my Church” (Matt. 16:18). After the Resurrection He confirmed Peter’s authority over the Church, saying to him: “Feed my lambs; feed my sheep” (John 21:15-17).
This promise and mandate did not end with Peter’s death. There has been an unbroken line of successors to Saint Peter – the Popes. As much as Saint Peter, the Pope is the rock on which Christ builds His Church, and he has the same mandate to feed the flock of Christ.