Chrysostom points out that the Lord takes the disciples outside the borders of Judea into the territory of the Gentiles to examine them on his identity. Epiphanius the Latin comments that the Father revealed the truth to Peter in the land of the Gentiles, which was a foretaste of what was to come. Theodore of Heraclea points out the significance of Jesus calling himself the Son of Man, highlighting the fact that Jesus in unchangeably man without ceasing to be God. He signifies, according to Chrysostom, how earnestly he desires the triune economy to be confessed. Theodore of Mopsuestia writes that at this stage his disciples were not all clear who he was, with some thinking he might be John the Baptist risen (as Herod did) or Elijah returned, or even Jeremiah.
St Cyril of Alexandria points out that Peter did not say ‘you are a Christ’ or ‘a son of God’, for many are they who have, by Grace, become these things by adoption; but there is only one who is by nature the Son of God. Peter indicates that Jesus is the one with power over life and death and in whom all authority lies.
Jesus says that Peter’s confession is the rock, and that on this rock he will build his church. This, according to Theodore of Mopsuestia, means that Jesus builds his church on this same confession of faith. For this reason, Jesus changes the name of the Apostle from Simon to ‘Peter’, which in the Aramaic means ‘rock’, to signify his authority. To him and the church are given the keys to the kingdom. He who is a member of the church has access to the kingdom; he who is not, does not.
Christ, Epiphanius, writes, is the rock which is never worn away of can be destroyed. Peter gladly receives his new name to signify the established and unshaken faith of the Church. The devil will forever seek to undermine the church, but he will fail because it is based on unshakable foundations.
St Leo the Great comments that in saying that the Father has revealed to Peter the truth of his identity, Jesus goes on to to invest Peter with authority. Of course Jesus is the cornerstone and the rock, but he now says to Peter: “you also are rock because you are made firm with my strength. What properly belongs to me, you share with my by participation”. This confession will not be restrained even by the very gates of hell, for it is a declaration of life. It lifts up to heaven those who confess it, and those who deny it sink into hell. The right to bind and loose is given to all the Apostles, but it is entrusted in a unique way to the one whose name is changed to signify he is the rock chosen by Jesus.