The Rock and the Cornerstone

Message for the Thirteenth Sunday after Pentecost, Year A (8/27/2023)

Matthew 16:13-20


You may know that Bethany and I both attended graduate school in Chicago, a place we learned to love deeply and plan to visit regularly. There are any number of reasons you should see Chicago, too, not the least of which is Sue. Who is Sue, you might ask? She resides at the Field Museum on Lakeshore Drive downtown. And, she can never leave, because Sue is a skeleton of Tyrannosaurus rex. In fact, she’s the largest that has ever been found, as well as the most complete at about 90%. Paleontologists love Sue because she’s an excellent specimen for studying the species, and the Field Museum can produce replicas of her skeleton to share with dinosaur lovers everywhere. Sue is arguably the most famous fossil in the world.[1]

Dinosaur fossils are bones turned to stone, as mineral-rich water seeped into the animals’ remains over tens of millions of years and transformed them into something much harder.[2] We sometimes call this process petrification, from the Greek word petra, for rock. Fossils are windows into the distant past, remnants of ancient creatures and peoples that tell us a great deal about who they were and how they lived.

This brings me to Simon, that disciple whom Jesus called “Peter,” Petros– a title or nickname, not a proper name. “Blessed are you, Simon son of Jonah,” Jesus declares in our Gospel from Matthew today, “I tell you, you are Petros, and on this petra I will build my church….”

Maybe we should have called Simon “Stony” in English instead of “Peter,” or “Simon the Rock,” in order to get the point across. In any case, if I were to subtitle this passage, I’d call it “Simon is petrified.” And, I don’t mean that Simon is afraid, although that’s certainly the case in other episodes in Matthew. By “Simon is petrified,” I mean that he becomes a fossil of sorts, a lasting example of faith for future generations to rediscover.

Although he’s named first among the Twelve Apostles and credited with key leadership in the early church, Simon Peter’s prominence in the sacred story is not a matter of special merit. As we’ll discover in the very next scene, the Gospel for next Sunday, at this point in the story Peter fundamentally misunderstands Jesus’ purpose. He gets the title right: “You are the Messiah, the Son of the living God.” But, he doesn’t know what that title means; neither does he grasp what the Messiah’s fate will be.[3] And, lest we forget that he’s in the same boat with all the other disciples, so to speak, keep in mind that Peter is the one who denies Jesus at that critical moment just prior to the crucifixion.[4]

Peter’s faith is not a hard-won achievement, but a gift of God. “Blessed are you,” Jesus replies to Peter’s confession in our Gospel today, “for flesh and blood have not revealed this to you, but my Father in heaven.” In other words, Peter doesn’t discern Jesus’ messianic identity because he is wiser or more insightful than the others; rather, he is the recipient of God’s gift of revelation. The apostle Paul puts it plainly: “No one can say ‘Jesus is Lord’ except by the Holy Spirit.”[5]

And, if Peter’s faith is a gift, then so is his place in the Christian story. Today’s Gospel is famous for Peter’s confession of faith: “You are the Messiah, the Son of the living God.” But, Jesus also confesses faith in Peter: “Blessed are you, Simon, Son of Jonah…. You are Petros, [the rock,] and on this rock I will build my church.” In other words, You have been petrified, preserved as a model for disciples to come; I believe in you. In spite of Peter’s foibles, in other words, Jesus entrusts to him the sacred work of God’s kingdom; Jesus calls him to be a paradigm of faith for posterity.

Of course, Peter is a rock only because Jesus is the Rock, the foundation on which the whole structure is built. “See, I am laying in Zion a stone,” Peter quotes the prophet Isaiah in his first letter, “a cornerstone chosen and precious; and whoever believes in him will not be put to shame.”[6] The seventh-century theologian Bede put it this way: “This [first] rock, that is, the Lord Savior… gave to [Simon] who knew him, loved him, and confessed him, the privilege of sharing his name….”[7] If Simon is petrified, in other words– if Simon is the Rock– it’s only because Christ is the Cornerstone.

And in this way, Peter stands in for all of us. He represents the enduring privilege and challenge of discipleship. “Come to [Christ], a living stone,” he writes, “though rejected by mortals yet chosen and precious in God’s sight, and like living stones, let yourselves be built into a spiritual house….”[8] That is to say, you are a rock, and the person sitting next to you is a rock, and you who are worshiping online, and the one sitting next to you, and on these rocks God will continue to build the church, the spiritual house where the living Christ chooses to dwell in every generation. Membership in this house is not a mark of privilege, but a gift of grace.

So, thanks be to God, who gives us a glimpse of Christ in word and sacrament, and thus inspires our faith. Thanks be to God, who blesses us and gives us many and various gifts. Thanks be to God, who calls us, like Peter and the first disciples, into a life of purpose for the sake of the kingdom come on Earth as in heaven.[9]



[3] Matthew 16:21-28.

[4] Matthew 26:69-75.

[5] 1 Corinthians 12:3.

[6] 1 Peter 2:6; Isaiah 28:16. See also 1 Corinthians 10:4.


[8] 1 Peter 2:4-5.

[9] See M. Eugene Boring, The New Interpreter’s Bible, Vol. VIII, 347.

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