How do Catholics answer this Patristic Exegesis of the Rock of Matthew 16:18 compiled by William Webster? As a Catholic I am a bit confused.
Remember, in this man Peter, the rock. He’s the one, you see, who on being questioned by the Lord about who the disciples said he was, replied, ‘You are the Christ, the Son of the living God.’ On hearing this, Jesus said to him, ‘Blessed are you, Simon Bar Jona, because flesh and blood did not reveal it to you, but my Father who is in heaven. And I tell you’…’You are Peter, Rocky, and on this rock I shall build my Church, and the gates of the underworld will not conquer her. To you shall I give the keys of the kingdom. Whatever you bind on earth shall also be bound in heaven; whatever you loose on earth shall also be loosed in heaven’ (Mt 16:15-19). In Peter, Rocky, we see our attention drawn to the rock. Now the apostle Paul says about the former people, ‘They drank from the spiritual rock that was following them; but the rock was Christ’ (1 Cor 10:4). So this disciple is called Rocky from the rock, like Christian from Christ.
Why have I wanted to make this little introduction? In order to suggest to you that in Peter the Church is to be recognized. Christ, you see, built his Church not on a man but on Peter’s confession. What is Peter’s confession? ‘You are the Christ, the Son of the living God.’ There’s the rock for you, there’s the foundation, there’s where the Church has been built, which the gates of the underworld cannot conquer.
John Rotelle, O.S.A., Ed., The Works of Saint Augustine (New Rochelle: New City Press, 1993), Sermons, Volume III/6, Sermon 229P.1, p. 327.
He, then, who before was silent, to teach us that we ought not to repeat the words of the impious, this one, I say, when he heard: ‘But who do you say I am,’ immediately, not unmindful of his station, exercised his primacy, that is, the primacy of confession, not of honor; the primacy of belief, not of rank…This, then, is Peter who has replied for the rest of the Apostles; rather, before the rest of men. And so he is called the foundation, because he knows how to preserve not only his own but the common foundation. Christ agreed with him; the Father revealed it to him. For he who speaks of the true generation of the Father, received it from the Father, did not receive it from the flesh. Faith, then, is the foundation of the Church, for it was not said of Peter’s flesh, but of his faith, that ‘the gates of hell shall not prevail against it.’ But his confession of faith conquered hell. And this confession did not shut out one heresy, for, since the Church like a good ship is often buffeted by many waves, the foundation of the Church should prevail against all heresies. The day will fail me sooner than the names of heretics and the different sects, yet against all is this general faith-that Christ is the Son of God, and eternal from the Father, and born of the Virgin Mary.
The Fathers of the Church (Washington D.C.: Catholic University, 1963), Saint Ambrose, The Sacrament of the Incarnation of Our Lord 4.32-5.35, pp. 230-1.
I know moreover that not only this thing saddens you, but also the fact that while others have obtained the churches by violence, you are meanwhile cast out from your places. For they hold the places, but you the Apostolic Faith. They are, it is true, in the places, but outside of the true Faith; while you are outside the places indeed, but the Faith, within you…But ye are blessed, who by faith are in the Church, dwell upon the foundations of the faith, and have full satisfaction, even the highest degree of faith which remains among you unshaken. For it has come down to you from Apostolic tradition, and frequently has accursed envy wished to unsettle it, but has not been able. On the contrary, they have rather been cut off from their attempts to do so. For thus it is written, ‘Thou art the Son of the Living God,’ Peter confessing it by revelation of the Father, and being told, ‘Blessed art thou Simon Barjona, for flesh and blood did not reveal it to thee, but My Father Who is in heaven,’ and the rest. No one therefore will ever prevail against your Faith, most beloved brethren.
Philip Schaff, Nicene and Post Nicene Fathers (Grand Rapids: Eerdmans, 1953), Volume IV, St. Athanasius, Letters of Athanasius, Letter 29, p. 551.
More exegesis can be read in here