Augustine interpreting Matt 16:18 like a Protestant and not like the popes religion claiming the Rock is Christ and the church is built on Peter's confession and not on Peter.
"For before he was called Simon. Now this name of Peter was given him by the Lord, and that in a figure, that he should signify the Church. For seeing that Christ is the rock (Petra), Peter is the Christian people. For the rock(Petra) is the original name. Therefore Peter is so called from the rock; not the rock from Peter; as Christ is not called Christ from the Christian, but the Christian from Christ. Therefore, he says, You are Peter; and upon this Rockwhich you have confessed, upon this Rock which you have acknowledged, saying, You are the Christ, the Son of the living God, will I build My Church; that is upon Myself, the Son of the living God, will I build My Church. I will build you upon Myself, not Myself upon you.
2. For men who wished to be built upon men, said, I am of Paul; and I of Apollos; and I of Cephas, who is Peter. But others who did not wish to be built upon Peter, but upon the Rock, said, But I am of Christ. And when the Apostle Paul ascertained that he was chosen, and Christ despised, he said, Is Christ divided? Was Paul crucified for you? Or were ye baptized in the name of Paul? And, as not in the name of Paul, so neither in the name of Peter; but in the name of Christ: that Peter might be built upon the Rock, not the Rock upon Peter."
Augustine--Sermon 26 Ch. 1 & 2