Augustine wrote several passages which deal with the question of whether Peter was the Rock. His mature conclusion was that the Rock is Christ.
“In one place I said… that the Church had been built on Peter as the Rock… but in fact it was not said to Peter, “Thou art the Rock,” but rather “Thou art Peter.” The Rock was Jesus Christ, Peter having confessed Him as all the Church confesses Him, He was then called Peter, “the Rock”… (ed, for his faith) …Between these two sentiments let the reader choose the most probable.”
St. Augustine, Retractions - 13th Sermon; Contra Julianum 1:13
St. Augustine adds:
"Peter had not a primacy over the apostles, but among the apostles, and Christ said to them “I will build upon Myself, I will not be built upon thee.”
**These comments by Augustine are highly significant. ** They are the fruits of his mature reflection and belong to his work of “Retractions” in which he corrects the former doctrinal errors of his earlier years. These comments totally demolish the Roman Catholic claim that the early Church Fathers taught what is now the modern Catholic teaching as regards the papal office.
Here we have the greatest theologian of the West writing**, after 400 years of the Church’s existence, that Peter is not the rock. ** Augustine allows such an interpretation, but he himself denies it. Would he have been in a position to deny it if the Church had believed it during the preceding 400 years??!
How does one explain this?