Who Is the Rock in Matthew 16:18?

Some have asserted the word “rock” in Gospel of Matthew (Chapter 16:18) refers exclusively either to Jesus Christ or to Peter’s profession of faith, but not to Peter himself.

To support their position, they point to the fact that two different forms of the noun appear in the Greek rendering of the verse—petros and petra. Insisting the former means “small stone” and the latter “large stone,” they contend that Jesus actually said, “You are Small Stone [Petros], and on this large stone [petra] I will build my church.”

Of course, this interpretation twists Jesus’ simple and clever play on words into a disjointed conundrum. Fortunately, there is a better explanation for the discrepancy. To begin with, Saint Matthew’s Gospel was written either in Hebrew or Aramaic, not in Greek.¹ That Greek assigns gender to words posed a certain difficulty for the scribes, who later translated the Gospel into that language, as petra, a feminine word, was unfit to serve as the Apostle’s name.

As a way around this problem, petra was given a masculine ending, making it Petros. The choice of the scribes on this matter is ultimately irrelevant, however, since Jesus spoke Aramaic, not Greek. And, as Gospel of John (1:42) proves, Jesus did not call Peter “Petros,” but Kepha (rendered phonetically in Greek as Cephas), the Aramaic word for “large stone” or “rock.” What Jesus said in Matthew 16:18, then, is simply, “You are Rock [Kepha], and on this rock [kepha] I will build my church.”

That Peter is the “rock” of the Church does not undermine the truth that Jesus is the Church’s true foundation per St. Paul’s First Letter to the Corinthians (3:11), anymore than calling Abraham the “father of many nations” in Genesis, 17:5, undermines the Fatherhood of God (“call no man ‘Father'” in the Gospel of Matthew, 23:9).

Consider that Peter calls Jesus “that living stone” and in the next breath exhorts the faithful to be “like living stones” (see Peter’s First Epistle, 2:4, 5).

Pope Boniface VIII (1294-1303) declared, “Of this one and only Church there is one body and one head—not two heads, like a monster—namely Christ, and Christ’s vicar is Peter, and Peter’s successor” (Unam Sanctam).

Peter and the Apostles are the foundation of the Church (see Matthew, 16:18; The Book of Revelation, 21:14;  and Isaiah, 51:1-2) only inasmuch as God conferred this quality upon them.

Peter’s rock-likeness is wholly dependent upon Christ’s rock-likeness; Christ’s rock-likeness is inherent to His divinity. As a rock, Peter is subject to Christ; Christ the Rock is subject to no one and nothing.