TWH: There's a whole issue surrounding the historicity of the confession of Peter found in John 6. In this post, we want to focus not on whether or not such a confession took place per se, but whether the confession in John 6 is "retweet" of the confession found in Matthew 16, albeit with some adaptation for John's audience. Someone is bound to ask, so I'll go ahead and show some of my cards: I believe that (1) the confession in John 6 is historical, (2) occurred as John described, and (3) is distinct from the event described in Matthew 16, which is also historical and occurred as described by its author.
The first thing we need to consider is the actual content of the confessions:
Matthew 16:16: σὺ εἶ ὁ χριστὸς ὁ υἱὸς τοῦ θεοῦ τοῦ ζῶντος (“You are athe Christ, the Son of the living God”)
John 6:68–69: πρὸς τίνα ἀπελευσόμεθα; ῥήματα ζωῆς αἰωνίου ἔχεις, καὶ ἡμεῖς πεπιστεύκαμεν καὶ ἐγνώκαμεν ὅτι σὺ εἶ ὁ ἅγιος τοῦ θεοῦ (“Lord, to whom else would we go? You have words of eternal life. We have believed and have come to know that you are the Holy One of God”)When we consider the textual evidence, we find out really quick that some people saw an issue related to these two passages. This isn't a "modern" issue per se. Pretty early on in the transmission of the New Testament texts, some scribes wrestled with what they found in this Gospel at this point in the text. Some scribes were either open to the possibility that John adapted the Matthew 16 discourse for his own purposes, and in doing so made an effort to "correct" the text and preserve the original account as found in Matthew, or they felt that a copyist before them had tweaked the passage and got away from the event they felt was the actual event, as recorded in Matthew. In the manuscripts we find a number of different readings. In place of ὁ ἅγιος τοῦ θεοῦ we find the following variant readings (some mss. have a slight variation of the three provided below):
ὁ χριστός ("the Christ")
ὁ χριστός ὁ ἅγιος τοῦ θεοῦ ("the Christ, the Holy One of God")
ὁ χριστός ὁ ἅγιος τοῦ θεοῦ τοῦ ζῶντος ("the Christ, the Holy One of the Living God")It doesn't take much effort to see the attempt to reconcile the John 6 passage to the text of Matthew 16. We have the insertion of "Christ," the insertion of "living," and both in other mss.
The reading found in the NA critical text (not the variants mentioned in the apparatus) is most likely the original reading. It has both date and geographical distribution in its favor when it comes to the external evidence, and when we think about the internal evidence, the presence of "Christ" and "living" is easier to explain as an attempt to harmonize the passages.
The next thing we need to consider is the context in which the passages are found. The confessions occur in very close proximity to one another, but not in the exact locations in the chronology of Jesus' life and ministry. Here's are the events leading up to the first confession: (1) The crowds attempt to install Jesus as king––by force (Matt. 14:22–23//Mark 6:45–46//John 6:14–15; (2) Jesus walks on water (Matt. 14:24–33//Mark 6:47–52//John 6:16–21); (3) Jesus heals at Gennesaret (Matt. 14:34–36//Mark 6:53–56); (4) One of Jesus' long teaching discourses (John 6:22–71), in which we find the first confession of Peter. What do the Gospels say happens after this point? Well, we have a conflict about ceremonial cleanliness, the account of the Gentile woman in Tyre and Sidon, some healings in Decapolis and the feeding of the four-thousand (remember Jesus didn't get very far off the beach in Mark as he headed towards Decapolis), followed by the return to the northwestern region of the Sea of Galilee. It is at this point, after Jesus heals a blind man at Bethsaida, that Jesus withdraws with his disciples to Caesarea Philippi, and it is there that we find the second confession of Peter. So as you can see, the events of John 6 and Matthew 16 are close together in the overall chronology of Jesus' ministry, but they are not found in identical places. That's another argument in favor of two distinct confessions.
The closer context in the individual pericopes also presents numerous differences, beyond those dealing with the actual confessions. For example, the backdrop of the confession in Matthew is Caesarea Philippi. Idols were placed inside placeholders carved directly into the rock along the road leading in and out of the city. This would have been quite a place for Jesus to ask his disciples who people said that he was. Another distinction deals with the questions leading up to the confessions. In Matthew, Jesus asks specifically who people said that he was. In John, he asked them if they wanted to join the crowds who had just departed on account of the "harsh statement" in his teaching. In Matthew, the disciples are on a retreat with Jesus, away from all of the crowds.
There are numerous reasons to view this as a second confession. What's striking is Jesus' response to the declaration in Matt. 16:16 and how he acknowledged that God the Father had revealed to Peter Jesus' supreme identity. The title of Son was far more significant than the title of "Holy One," at least we can gather as much based on the way that Jesus responded. The latter, even if it is a messianic title (which I think is reasonable to believe that it is), focuses on his character and his sinlessness. The former though focuses on this absolutely unique and eternal relationship among the members of the Godhead. Though the kings of Israel and even Israel itself had been referred to as God's son, it was always in a metaphorical sense. When applied to Jesus, it was never metaphorical. He is God's Son, eternally and always.