Matthew 16:18, of course, is the famous proof-text used by Roman Catholics to “prove” that Peter was the first pope. Ulrich Luz, a leading commentator on the Gospel of Matthew, is author of the three-volume Hermeneia Commentary on Matthew series.
What follows is from Chapter 4 of his work, “Matthew in History: Interpretation, Influence, and Effects” (Minneapolis, MN: Augsburg Fortress Press ©1994), Chapter Four: “Peter: The True Christian or the Pope (Matthew 16)”:
There are four main types of interpretations of Matt. 16:18 in the history of exegesis.
1. The first is the typological interpretation, which is not only the oldest that we know but the “mother” of two other types of interpretation. We could call it the “democratic” interpretation of Matt. 16:18. Its classical representative is Origen. According to him, Peter symbolizes every true, spiritual Christian. He says, “A rock is every disciple … who drank of the spiritual Rock [Christ], who followed them” (1 Cor 10:4 [citing Origen’s Commentary on Matthew 12.10]). Elsewhere Origen says that the church is built on the word in every human being, and, in this way, every Christian becomes strong like a rock [citing Contra Celsum 6.77]. According to this interpretation, Peter is the type of the true, spiritual, and perfect Christian.
This interpretation was also widespread in Christian Gnosticism. There Peter is the prototype of the true Gnostic, who received his knowledge through revelation from the spiritual world [see Apocalypse of Peter, Nag Hammadi Codex VII, 71, 14–72, 4]. Even Tertullian, who was decidedly antignostic, also understood the authority given to Peter as the authority of every spiritual Christian De Pudicitia 21].
The typological interpretation was the basis of two other main types of interpetations, the classical Eastern and the classical Western interpretations.
Keep in mind that both Tertullian and Origen wrote later than the publication of the apocryphal “Acts of Peter” (circa 180 AD) – and that Origen actually quotes from this admittedly fictitious work in his Commentary on Genesis – also cited in Hippolytus – this is only a portion of what Eamon Duffy has in mind as he notes “These stories were to be accepted as sober history by some of the greatest minds of the early Church — Origen, Ambrose, Augustine. But they are pious romance, not history, and the fact is that we have no reliable accounts either of Peter’s later life or the manner or place of his death…”
Here is what Markus Bockmuehl, the Cambridge scholar who has most recently (2010, 2012) done extensive surveys of Peter and “Petrine” literature:
Peter’s crucifixion “upside down” … surfaces late in the second century as a powerfully subversive political trope in the Acts of Peter and then in Hippolytus and in Origen (who came to Rome in 212). It is difficult to be certain in what sense it expresses living memory (Markus Bockmuehl, “The Remembered Peter”, Tübingen, DE: Mohr Siebeck ©2010, pg 131).
We should be clear here, it was not Origen’s “interpretation” that was the “pious romance” of the papacy – rather, it turned out to be his passing along of the story from the Acts of Peter.
Continuing with Luz:
2. The Eastern interpretation In the Greek and Syrian churches, the rock was interpreted as the confession or the faith of Peter. Historically this is a development of Origen’s typological interpretation. In identifying this rock upon which every perfect spiritual Christian is founded, Origen already pointed to faith. Tertullian also could interpret Peter as the one who guarantees unaltered and public apostolic tradition. According to Theodore of Mopsuestia, the confession of Peter “does not belong to Peter alone, but was for all people. When Jesus called his confession a rock, he clarified that it is upon this [confession] that he wanted to build his church.” This interpretation does not contest that Jesus’ promise was given to Peter personally, but it puts the emphasis on the application of this gift. The question was, “How is Peter the rock of the church?”
The answer refers exegetically to his confession in Matt. 16:16. But it is also a contextual answer to the situation of the church in the fourth century. The church then had to defend its true identity by refuting the claims of the heretics. In this situation the basic Christian confession of the divine sonship of Jesus was really the rock upon which the church was built. Also in later centuries, under Islamic dominion, the tradition confession remained the rock of the Eastern churches that secured their identity. This interpretation corresponded not only to the text but also to the needs of the situation.
This interpretation focusing on Peter’s confession was widespread not only in the East; Ambrose, Hilary, and Ambrosiaster made it known also in the West. In one of his early writings, Ambrose added the significant observation that Peter had a primacy “of confession …, not of honor; … of faith, not of order” [De Incarnationis dominicae sacramento 4.32 = CSEL 79.238f.] Here we have a trace of anti-Roman polemics, which was unusual at that time but might have been necessary in northern Italy. The Eastern interpretation remained known and popular in the West throughout the Middle Ages. Usually it had no anti-Roman accent. The reason for this was that the Roman interpretation of our text was so marginal and unknown that it was not necessary to be preoccupied with it. Only in the late Middle Ages, as a protest against pontifical claims, could it be said that the confession of Peter and not Peter himself was the rock. With this new focus, such an interpretation was used also by the Reformers. But it is not, as is often said, the Reformation interpretation; it was the most ecumenical interpretation of that time.
What were the functional effects of this interpretation? It strengthened the identity of the church, based on the traditional confession, whereas the earlier Origenistic interpretation strengthened the identity of the individual Christian. That it strengthened the position of the opponents against Rome was only a later side effect. Their position not to accept the exclusive authority of the pope was justified precisely by referring to Matt. 16.18
3. Origen and Tertullian are also the ancestors of the other important type of interpretation hat dominated the Western exegesis of the Middle Ages, the Christological interpretation [see also Origen Commentary on Matthew 12.10 = GCS Origenes 10.86; Tertullian, de Praescriptione Haereticorum 22.4]. Its real father is Augustine. For him, the rock of the church is not Peter but Christ himself. Texts like 1 Cor 10:4 and 1 Cor. 3:11 were decisive for him. Peter is not the rock, but, as a believer in Christ and as the first apostle, he represents the church. It is not, he could say, that the rock took its name from Peter, but Peter had his name from the petra, the “rock.” Augustine’s interpretation expressed his doctrine of grace, because Peter, and in him the whole church, is built upon Crist alone. This Christological interpretation of the rock was very successful. It became the dominant interpretation of the Western church in the Middle Ages. It was not antipapal, because Augustine was a supporter of the Roman church. Most medieval conmmentators seem to have no idea that Matt 16.18 could refer to the pope. Thomas Aquinas, whose sympathies for the pope and polemics against the Eastern churches are well known, is one of the few exceptions.
Not that Aquinas had any great insight, however. As Hans Küng notes (“Infallible? An Inquiry”, Garden City, NY: Doubleday & Company, Inc., ©1971, originally published in German in 1970 under the title, Unfehlbar? Eine Anfrage, ©1970 by Benziger Verlag), “For all the indisputable merits of Aquinas in regard to theology as a whole, this point must be made clear. In his opusculum, Contra errors Graecoru, which he wrote in 1263, commissioned by the Curia, for Pope Urban IV and the negotiations for union with the Emperor, Michael VII Palaelogus, he presents to the weak Greeks the argument for the Roman rights in an exorbitant way, and this had its effect also in the West. In connection with the sublime questions of Trinitarian doctrine, in several chapters toward the end of the work, which positively in quotations from forgeries, it is “shown” “that the Roman Pontiff is first and greatest of all bishops,” “that the same Pontiff presides over the whole Church,” “that he has the fullness of power in the Church,” “that the same power conferred by Christ on Peter the Roman Pontiff is the successor of Peter.” For those Roman Catholics who are inclined to disregard everything from Küng indiscriminately, Küng provides copious footnotes on this.
Continuing with Luz:
Rarely in the Middle Ages but fore frequently in the Reformation, the Augustinian interpretation became an argument to refute the pontifical interpretation: Christ, and not the pope, is the rock. Christ wanted to have one rock only; the adherents of the pope have two, says Luther. When the Reformers took over the Augustinian interpretation, they created nothing new but continued the traditional interpretation of the church and gave it an anti-Roman emphasis.
What were the effects of this interpretation? For Augustine it was the result of an exegetical and theological reflection. He read our text “canonically” in the light of the entire New Testament, including Pauline texts like 1 Cor. 3:11; 10:4. For him Christ is the sole basis of the church. One of the reasons for the popularity of this interpretation may have been that it enabled an easy identification of the Christians with Peter; he is a human being, weak and unstable, not perfect, and he is built upon Christ alone. In Christ the human church and the human, imperfect Christians have their basis. I think that this interpretation was effective because it was a sincere and clear expression of Christian piety.
4. The Roman interpretation: Probably in the first part of the third century, the claims of the Roman church to special authority and dignity were legitimated for the first time by Matt. 16:18. The earliest testimonies are unclear. Well known is Tertullian’s polemic against the “apostolic Lord” who claims for himself and every church “near to Peter” the authority to bind and loose sins like Peter [De Pudicitia 21], but it is disputed whether it really is Bishop Callistus of Rome whom he opposes. Less well known is Origen’s polemic against people who think that “the keys of the kingdom of heaven are given to Peter only. Again, unfortunately, we do not know of whom Origen was thinking. The first clear testimony of verse 18 being applied to the bishop of Rome is Stephen (pope, 254–257). [Firmilian, writing to Cyprian], who sees Peter as the model of all bishops, comments [that this usage of the verse is] “An open and manifest [folly]” [see section 17].
Until the middle of the fifth century we have only a few other testimonies. The famous interpretation of Pope Leo I is interesting because he combines his pontifical interpretation not with the idea of apostolical succession but with a kind of Petrine mysticism. He did not understand himself primarily as successor of Peter, but as his revivification. Today it is admitted, even by Roman Catholic research, that this Roman interpretation is an exegetical form of “secondary legitimation.” It sought to legitimize the claims to primacy on the part of the Roman church that have other reasons, such as the fact that Rome was … a center of orthodoxy, had the graves of two apostles, and so on. Less known is the fact that during the Middle Ages this Roman interpretation played a very minor role. According to Karlfried Frölich, it was known almost exclusively in certain [largely] forged decretals and is mentioned there only with the goal of supporting papal claims. In the medieval commentaries it is almost nonexistent.
There’s that phrase that I use: “nonexistent”.
Continuing with Luz:
The Roman interpretation was entertained not by the whole Western church but in a more limited sense by its Roman leaders. Its Sitz im Leben was and remains the justification of papal claims. It probably owes its final success in the church to the very fact that it was an interpretation articulated by its rulers. An important step toward this success was taken in the sixteenth and seventeenth centuries. In the controversies with the Protestants, the popes needed this interpretation for their own legitimation against the Protestant use of the hitherto standard Augustinian and Eastern interpretations of the text. Only in the Catholic Reformation of the sixteenth and seventeenth centuries did the Roman interpretation become dominant in Roman Catholic exegesis. The first exegete who propagated it was Cajetan; the most influential book was the defense of the primacy of the pope by Bellarmine [pg 68].
Luz relates that “at the first Vatican Council this ‘late rereading of Scripture’ finally prevailed”.
Later Luz says, “I think that no other interpretation is so far from the New Testament text as this one”. It is justified only in “belong[ing] to the freedom given by the Spirit that new experiences, new historical situations, and new demands create not only new interpretations but new institutions” [pg 72].
See also Turretinfan’s response to Bryan Cross on the unanimous consent of the fathers.