It's quite simple:
"I understand your thinking," he said, "but you Catholics misunderstand this verse because you don’t know any Greek. That’s the trouble with your Church and with your scholars. You people don’t know the language in which the New Testament was written. To understand Matthew 16:18, we have to get behind the English to the Greek."
"Is that so?" I said, leading him on. I pretended to be ignorant of the trap being laid for me.
"Yes," he said. "In Greek, the word for rock is petra, which means a large, massive stone. The word used for Simon’s new name is different; it’s Petros, which means a little stone, a pebble."
In reality, what the missionary was telling me at this point was false. As Greek scholars—even non-Catholic ones—admit, the words petros and petra were synonyms in first century Greek. They meant "small stone" and "large rock" in some ancient Greek poetry, centuries before the time of Christ, but that distinction had disappeared from the language by the time Matthew’s Gospel was rendered in Greek. The difference in meaning can only be found in Attic Greek, but the New Testament was written in Koine Greek—an entirely different dialect. In Koine Greek, both petros and petra simply meant "rock." If Jesus had wanted to call Simon a small stone, the Greek lithos would have been used. The missionary’s argument didn’t work and showed a faulty knowledge of Greek. (For an Evangelical Protestant Greek scholar’s admission of this, see D. A. Carson, The Expositor’s Bible Commentary [Grand Rapids: Zondervan, 1984], Frank E. Gaebelein, ed., 8:368).
"You Catholics," the missionary continued, "because you don’t know Greek, imagine that Jesus was equating Simon and the rock. Actually, of course, it was just the opposite. He was contrasting them. On the one side, the rock on which the Church would be built, Jesus himself; on the other, this mere pebble. Jesus was really saying that he himself would be the foundation, and he was emphasizing that Simon wasn’t remotely qualified to be it."
"Case closed," he thought.
It was the missionary’s turn to pause and smile broadly. He had followed the training he had been given. He had been told that a rare Catholic might have heard of Matthew 16:18 and might argue that it proved the establishment of the papacy. He knew what he was supposed to say to prove otherwise, and he had said it.
"Well," I replied, beginning to use that nugget of information I had come across, "I agree with you that we must get behind the English to the Greek." He smiled some more and nodded. "But I’m sure you’ll agree with me that we must get behind the Greek to the Aramaic."
"The what?" he asked.
"The Aramaic," I said. "As you know, Aramaic was the language Jesus and the apostles and all the Jews in Palestine spoke. It was the common language of the place."
"I thought Greek was."
"No," I answered. "Many, if not most of them, knew Greek, of course, because Greek was the lingua franca of the Mediterranean world. It was the language of culture and commerce; and most of the books of the New Testament were written in it, because they were written not just for Christians in Palestine but also for Christians in places such as Rome, Alexandria, and Antioch, places where Aramaic wasn’t the spoken language.
"I say most of the New Testament was written in Greek, but not all. Many hold that Matthew was written in Aramaic—we know this from records kept by Eusebius of Caesarea—but it was translated into Greek early on, perhaps by Matthew himself. In any case the Aramaic original is lost (as are all the originals of the New Testament books), so all we have today is the Greek."
I stopped for a moment and looked at the missionary. He seemed a bit uncomfortable, perhaps doubting that I was a Catholic because I seemed to know what I was talking about. I continued.
Aramaic in the New Testament
"We know that Jesus spoke Aramaic because some of his words are preserved for us in the Gospels. Look at Matthew 27:46, where he says from the cross, ‘Eli, Eli, lama sabachthani?’ That isn’t Greek; it’s Aramaic, and it means, ‘My God, my God, why have you forsaken me?’
"What’s more," I said, "in Paul’s epistles—four times in Galatians and four times in 1 Corinthians—we have the Aramaic form of Simon’s new name preserved for us. In our English Bibles it comes out as Cephas. That isn’t Greek. That’s a transliteration of the Aramaic word Kepha (rendered as Kephas in its Hellenistic form).
"And what does Kepha mean? It means a rock, the same as petra. (It doesn’t mean a little stone or a pebble. What Jesus said to Simon in Matthew 16:18 was this: ‘You are Kepha, and on this kepha I will build my Church.’
"When you understand what the Aramaic says, you see that Jesus was equating Simon and the rock; he wasn’t contrasting them. We see this vividly in some modern English translations, which render the verse this way: ‘You are Rock, and upon this rock I will build my church.’ In French one word, pierre, has always been used both for Simon’s new name and for the rock."
For a few moments the missionary seemed stumped. It was obvious he had never heard such a rejoinder. His brow was knit in thought as he tried to come up with a counter. Then it occurred to him.
"Wait a second," he said. "If kepha means the same as petra, why don’t we read in the Greek, ‘You are Petra, and on this petra I will build my Church’? Why, for Simon’s new name, does Matthew use a Greek word, Petros, which means something quite different from petra?"
"Because he had no choice," I said. "Greek and Aramaic have different grammatical structures. In Aramaic you can use kepha in both places in Matthew 16:18. In Greek you encounter a problem arising from the fact that nouns take differing gender endings.
"You have masculine, feminine, and neuter nouns. The Greek word petra is feminine. You can use it in the second half of Matthew 16:18 without any trouble. But you can’t use it as Simon’s new name, because you can’t give a man a feminine name—at least back then you couldn’t. You have to change the ending of the noun to make it masculine. When you do that, you get Petros, which was an already-existing word meaning rock.
"I admit that’s an imperfect rendering of the Aramaic; you lose part of the play on words. In English, where we have ‘Peter’ and ‘rock,’ you lose all of it. But that’s the best you can do in Greek."
Beyond the grammatical evidence, the structure of the narrative does not allow for a downplaying of Peter’s role in the Church. Look at the way Matthew 16:15-19 is structured. After Peter gives a confession about the identity of Jesus, the Lord does the same in return for Peter. Jesus does not say, "Blessed are you, Simon Bar-Jona! For flesh and blood has not revealed this to you, but my Father who is in heaven. And I tell you, you are an insignificant pebble and on this rock I will build my Church. . . . I will give you the keys of the kingdom of heaven." Jesus is giving Peter a three-fold blessing, including the gift of the keys to the kingdom, not undermining his authority. To say that Jesus is downplaying Peter flies in the face of the context. Jesus is installing Peter as a form of chief steward or prime minister under the King of Kings by giving him the keys to the kingdom. As can be seen in Isaiah 22:22, kings in the Old Testament appointed a chief steward to serve under them in a position of great authority to rule over the inhabitants of the kingdom. Jesus quotes almost verbatum from this passage in Isaiah, and so it is clear what he has in mind. He is raising Peter up as a father figure to the household of faith (Is. 22:21), to lead them and guide the flock (John 21:15-17). This authority of the prime minister under the king was passed on from one man to another down through the ages by the giving of the keys, which were worn on the shoulder as a sign of authority. Likewise, the authority of Peter has been passed down for 2000 years by means of the papacy.
