Juan Maldonatus, Spanish Jesuit theologian in the 1500’s wrote about Mt. 16:18:
"There are among ancient authors some who interpret “on this rock,” that is, “on this faith,” or “on this confession of faith in which thou hast called me the Son of the living God,” as Hilary, and Gregory Nyssen, and Chrysostom, and Cyril of Alexandria. St. Augustine, going still further away from the true sense, interprets “on this rock,” that is, “on myself Christ,” because Christ was the rock. But Origen “on this rock,” that is to say, “on all men who have the same faith.” (source: Salmon, The Infallibility of the Church, pgs. 343-344)
The Hilary referred to above wrote in *De Trinitate *regarding Matt. 16:18:
“This faith it is which is the foundation of the church; through this faith the gates of hell cannot prevail against her. This is the faith which has the keys of the kingdom of heaven.”
and Augustine in his Retractiones:
"For it was not said to him: “Thou art a rock” (petra), but, “Thou art Peter" (Petrus); and the rock was Christ, through confession of whom Simon recieved the name Peter. Yet the reader may decide which of the two interpretations is the more probable.”
(Philip Schaff, 3:306)
Far from being dogmatic, Augustine left it up to the person to decide…
French theologian ordained priest in 1636, Jean de Launoy, surveyed the Church Fathers on this verse and found that 16 times the “rock” is identified as Christ, 44 times it’s identified as the confession of faith that Peter had just made, and only 17 times was the rock considered to be Peter (and you still have to take that to mean Petrine supremacy).
Even Catholic historians grant that the church Fathers were split on the interpretation of this passage.