Joseph Ratzinger, commenting on this passage, observes that our canonical Greek text must derive from an Aramaic original. There is a direct citation of Aramaic in the name “Simon Bar-Jonah”. There are also typical Aramaic phrases: “gates of the underworld”, “keys of the Kingdom”, “bind and loose”, “on earth and in heaven”. The word play on Simon’s new name “Rock” also works better in Aramaic than in Greek. Ratzinger concludes, against many contemporary liberal scholars, that we have here no anachronistic invention of the early Church, but on the contrary a direct echo of the very words of Jesus, memorably spoken on this most solemn of occasions.
After 21 centuries the Catholic Church continues to stand. She stands on the witness of SS. Peter and Paul, which does not change, because God does not change, and neither, come to that, does human nature. We celebrate SS. Peter and Paul, because to do so gives honour and glory to Jesus Christ the Lord, who chose them, and conferred his own authority on them; Jesus, whom they confessed, proclaimed, and bore witness to, even to the shedding of their blood.