On This Rock

This sermon was preached by Pastor Ted Carnahan for the Thirteenth Sunday after Pentecost on Sunday, August 23, 2026.

Now grace, mercy, and peace be with all of you from God our Father and from our Lord and Savior Jesus Christ. Amen.

Who do people say that I am?

Jesus asks the disciples who people say that he is, and the answers he gets—some of them make some sense, and some of them really don't. The first one given is John the Baptist. Now this one doesn't really pass the sniff test, but he didn't ask them what makes sense; he asked what people are saying about who Jesus is. And so one of the things they're saying is that Jesus is actually John the Baptist—and not just John the Baptist, but John the Baptist recently beheaded for telling the truth to King Herod, come back to life.

It's a strange answer, because Jesus and John the Baptist were almost exactly the same age. Remember that the Blessed Virgin Mary went to visit Elizabeth, her relative, and Elizabeth was already six months pregnant, and it was the in-the-womb John the Baptist who leapt for joy at hearing the voice of the Blessed Virgin Mother. And so they're relatives, born at almost the same time. So it doesn't really make sense. But still, people were saying that maybe this powerful prophet John the Baptist has somehow been reborn in Jesus.

A more reasonable answer is the second one: that perhaps this Jesus fellow is Elijah, who has come again. Remember that when Elijah leaves in the Old Testament, he doesn't actually die. Instead God sends chariots of fire, and Elijah gets on board and is carried up into heaven without dying. So the idea here is that Elijah went up into heaven without dying, and so now he has come again at the end of the age. It's time to usher in this new messianic kingdom, and Elijah the prophet has returned to point us in the right direction about this coming kingdom of God. Reasonable—but not correct.

And then there are those saying that maybe Jesus is Jeremiah come again, or one of the other prophets, because Jesus does seem to speak the word of God in a powerful and authoritative way. If Jesus is speaking with authority, then maybe he's somebody from the Old Testament we already know has the authority to say those things.

Who do you say that I am?

But then Jesus turns and asks them a different question. Instead of "Who do people say that I am?"—those other people, the ones who aren't here—he turns to the disciples, looks at them, and says, "Who do you say that I am?" And Simon Peter has the temerity, the guts, the impetuous nature to look Jesus in the eye and say, "You are the Christ, the Son of the living God."

What a claim! Because this is a claim that is going to get them in trouble. Among the Jews, to say that there is a son of the living God was something they could not accept. Among the Gentiles, to say that a Messiah has come is to say that Jesus is Lord and Caesar is not. This is a dangerous thing for Simon to say. But it is also true.

You know, at the end of days you are going to come to meet Jesus face to face, and when you do, you are going to be asked a question like that. You are going to be asked, "Who do you say that I am?" And ultimately no one can answer that question for you. You are the only person who can give the answer that is in your heart. Either Jesus is, in your faith, really the Christ, really the Son of the living God—or he is not.

Actions speak louder than words

And yet if we are honest with ourselves, if we take a good hard look at our own lives, if we think about the way we live and the things we do and the words that come out of our mouths—we are not often blessing God. We are not often living in a way that tells the truth that Jesus is the Son of the living God. In fact, if we take a careful, close look at the way we live, we deny Jesus Christ—his Messiahship, his being the Son of God—every day.

Not just every day; every hour! Every hour our sin testifies to what we really believe is the truth about Jesus. Our sin testifies against our faith. It would be easy to say, "Then you believe in Christ? Well then, why do you steal or commit adultery? Why do you dishonor God with your lips? Why do you tear down others, and so commit murder in your heart?" If you have any question whether you are a sinner who denies the reality that Jesus Christ is the Messiah, the Son of the living God, you need only look to the Ten Commandments and examine yourself with some honesty.

So when Peter gives his famous answer, it would be easy to imagine a rebuke instead. Peter says, "You are the Christ, the Son of the living God." It's beautiful—the confession of Jesus Christ, the true confession of our Christian faith. It would be so easy for Jesus to say, right on, Peter, well done. But it also would have been just as easy for Jesus to rebuke him immediately.

Think about it: Remember the reading from two weeks ago? Peter, if you know that I'm the Son of God—then when I called you out to walk on the water with me in the midst of the storm, and you said, "Lord, if it really is you, command me to come out onto the water," and I said, "Come," and Peter got out of the boat and started to walk on the water—he made it a couple of steps, and then he realized he was walking on water, and he wasn't really able to do that, and he began to sink. His faith was not as strong as that statement might lead you to believe.

Or just look back to last week's reading: if you know that I'm the Son of God, why were you one of the disciples gatekeeping access to Jesus just because the person asking for help wasn't Jewish?

There are plenty of examples from the recent past in this story where St. Peter could easily have been rebuked because the way he lived did not match the quality of his confession. Oh, Peter, you confess Christ so eloquently—but we know that your heart isn't perfectly in it.

And yet Jesus does not rebuke him. He doesn't point out Simon's inconsistency and weakness. Instead he does something even greater: he hands over the keys of the kingdom.

The Nickname

Because this confession is not something Peter discerned by his own power or understanding. He did not come up with this on his own. He didn't think this over, sit down and go, hmm, well, you know, carry the three, add plus C at the end—ah yes, "You are the Christ, the Son of the living God." No—it was revealed to him by God the Father. This faith that he is able to confess is not his own, not an achievement he has made, but a gift he has received. Flesh and blood has not revealed this to you, Simon, but my Father in heaven.

You are now to be called Peter—and the word Peter does mean rock. "You are Peter, and on this rock"—the rock of your confession—"I will build my church." Not on Peter himself; Peter is a shaky stone. We've seen that in his recent past, and we also see it in what we know is his future. Yes, Peter will steadfastly, boldly say, "Lord, even though all will abandon you, I will never abandon you." And Jesus says, "But you will deny me before others three times before the cock crows." And he does.

If confessing Christ were up to your cleverness or your courage, you'd fail the test. In fact, you do fail that test every day, just like Peter—by your sin, the words you speak and the actions you commit and the thoughts of your heart, you deny Jesus Christ. But on this rock—on the confession of Christ given by Simon Peter, "You are the Christ, the Son of the living God"—that is where Christian truth is found, where faith meets life.

And consequently, the church is not built on the quality of our believing; it is built on the object of our believing. It's not about how strong your faith is, how well you confess Christ, or how consistent your life is with the God whom you trust and believe in. Rather, it is that the one whom you trust is faithful. Jesus Christ, the Son of God, is faithfully for you.

The Rock from which you were hewn

I think this is what the prophet Isaiah is getting at in our reading this morning: "Look to the rock from which you were hewn." Look to Abraham and Sarah—one old childless couple—and God from them made a multitude. If God could build from that rock, if God could build from two old people having a child for the first time, he can build his church even out of deniers like you and me. The quarry God cuts his saints from has always been unlikely people. Consider the genealogy of Jesus: you have people who are murderers. You have Rahab the prostitute—rank sinners—from whom comes the Son of God. We are unlikely believers.

But we don't just stop there. Yes, okay, fine, it's true—I do deny Christ every day, every hour, by my thoughts, words, and deeds, by what I have done and by what I have left undone. Does that sound familiar, church? But the answer to this denial is not you screwing up your courage and making better choices, working harder at resisting sin, engaging your willpower, and being good instead of bad. Because if it were that, you could do it yourself—and frankly, you haven't. Instead, Jesus hands over the solution. The solution he hands over is the keys. He hands over the keys to the church, to Simon Peter and the other disciples. He says, "Here, take this. You're going to need it."

The Office of the Keys

The keys to the kingdom of heaven, the office of the keys, which is used to bind and loose sins. I give you the power of absolution—the absolution, the forgiveness of your sins that you do not earn or deserve, but which is given to you by the authority of Jesus Christ. And the authority of Jesus Christ is in those words, so that when they are spoken by the church to you, you may trust that they come to you as if from the lips of God himself. When we gather here and confess our sin at the beginning of the worship service, and I turn to you and I say—let me get to the exact phrasing here—"As a called and ordained servant of Christ, and by his authority, I therefore forgive you all your sins"—it is not because of my ability, or my holiness, or my being a shiny penny that the forgiveness of sins comes to you. The forgiveness of sins comes to you because it is the word of Jesus Christ, which has been entrusted to the church and is given to you—for you—for the comforting of your conscience and the reminder that you belong to God in Jesus Christ. So when you hear, "I forgive you all your sins," it's not just your pastor saying it; it is the voice of God speaking to you by the authority of Jesus Christ.

And when Jesus says that the gates of Hades will not prevail against his church, I think sometimes we get this backwards. We imagine the church is this fortress with fences and walls and gates, and the forces of hell are trying to invade, and we've got to keep them out. That's not the image here. It is Jesus saying that the church is storming the gates of hell. And all of us who, because of sin, have been locked in the prison of guilt and shame—all of us who have been held prisoner to darkness and the shadow of death can say in the face of the devil, confidently: "No. My Lord Jesus Christ has come to besiege this fortress of darkness. He leads a vast army, the hosts of heaven. There is no infernal bar that can hold back the rescuing crusade of my Lord Jesus Christ. He will break the bars that hold me in the power of sin. He will free me—and you, O devil, can't do a thing about it."

The confidence we have is ours because God's gift comes to us without our having paid for it. It is sheer grace. St. Paul says it well in Romans: "O the depth of the riches and wisdom and knowledge of God!" We didn't counsel God. We didn't give him a gift first. We didn't serve him first so that he might rescue us. For from him and through him and to him are all things. And then, having been rescued, we—out of gratitude for the love of God in Christ Jesus—are called to present our bodies as a living sacrifice, not to earn anything, but out of gratitude for the mercies of God.

So people, who do you say that Jesus is? The answer you give is found in how you live—not that you would earn your salvation, but that you would honor your Lord. The confession isn't just words; it's prophecy in proportion to faith, generosity, diligence, cheerfulness. Your confession of your Christian faith comes in how you treat others and how you worship the Lord Jesus Christ. Your answer is how you live your life—not just on Sunday morning, but the answer you give to the question all week long.

We've all been given different gifts. It doesn't look the same for each of us. As St. Paul gives the list: prophecy in proportion to faith, ministry in ministering, the teacher in teaching, the exhorter in exhortation, the giver in generosity, the leader in diligence, the compassionate in cheerfulness. All these things are different ways that we express gratitude to God for the gift given us in Christ. My way and yours aren't going to look the same, but this is why we are together—all of us belonging together in Christ, because all of us are like St. Simon Peter, desiring to trust and confess boldly, but also in this life struggling with sin.

Hear, then, the word of the Lord: bring him your denial. Confess your sin, admit the truth. You are not good, but God is good for you. Hear the word of forgiveness spoken to you. Christ, the Son of the living God, is for you. Therefore nothing will stand between you and the love of God in Jesus Christ. And know that you therefore are truly forgiven. And if truly forgiven by God in Jesus Christ, there is nothing in hell that can stand against it.

In Jesus' name, amen.