Catholics claim that the papacy is the key to Christian unity—the visible source of unity for God’s people. According to the Second Vatican Council, God has established the bishop of Rome as the Church’s “perpetual and visible principle and foundation of unity” (Lumen Gentium 88).
In his encyclical Ut Unum Sint, Pope St. John Paul II articulated the same belief in this way: “The communion of the particular churches with the church of Rome, and of their bishops with the bishop of Rome, is—in God’s plan—an essential requisite of full and visible communion” (97; emphasis added).
How can we explain this to non-Catholics? There are three kinds of evidence we can use: biblical, patristic, and evidence from reason. Let’s take the biblical first.
The Church’s understanding of the papal ministry as the principle of Christian unity is based on the historical evidence that Christ invested St. Peter with such a role.
The classic text is Matthew 16:18-19. There Jesus promises to build his Church on Peter, the rock, and ensures that the gates of hell would never prevail against it. He then gives Peter the “keys of the kingdom,” and says, “Whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.”
All the details present in this text reveal in some way that Christ wills Peter to be the visible source of unity for his Church. But for the sake of brevity, let’s simply highlight the part where Jesus makes him the foundational rock.
This pertains to Peter as the visible source of unity because you can’t separate a structure from the foundation on which it’s built. Since Jesus makes Peter the visible foundation, we can say that wherever you see Peter, there is the true Church of Christ. Therefore, to be united to Peter is to be united to Christ’s Church.
Some Protestants will object that Peter is not the rock, but that Christ is. Or they may say that Peter’s profession of faithis the rock. Catholics agree that both Jesus and faith in Jesus can be compared with a rock, but this doesn’t exclude its specific application to Peter in this case. And there are several reasons for this.
First, the new name that Jesus here gives to Simon (Peter, Gk. Petros) means rock. Elsewhere in the New Testament we see Peter referred to by the Aramaic equivalent of this name, Cephas (e.g. John 1:42). Why would Jesus change Simon’s name to “Rock” if he had nothing to do with the metaphorical Church-foundation rock Jesus is talking about in the very same sentence?
Second, Jesus uses the second-person singular pronoun (“you)” in reference to Peter seven times in the three verses that constitute the immediate context of the passage (Matt. 16:17-19). If everything applies to Peter both before and after the statement about the metaphorical rock, then it’s reasonable to conclude that the statement about the rock applies to Peter as well.
Denying that Peter is the rock also conflicts with the interpretation of writers in the first four centuries of Christianity, such as Tertullian, Origen, Cyprian of Carthage, Ephraim, and Hilary of Poitiers, all of whom affirm that Peter is the rock in Matthew 16:18.
Even major Protestant sources acknowledge that the Catholic interpretation is correct. For example, the New Bible Dictionary and the New Bible Commentary both acknowledge that the rock in Matthew 16:18 refers to Peter. The late Presbyterian professor Robert McAfee Brown, in A Pope for All Christians, admits that “Protestants are learning that the crucial passage in Matthew 16 about the ‘rock’ on which the church will be built almost certainly refers to Peter himself rather than to his faith.”
Another crucial text is Luke 22:31-32. Jesus informs the apostles that Satan desires to sift all of them like wheat. We know this because the Greek text uses the second-person plural pronoun, humas. However, when Jesus then speaks of his protection prayer, the Greek switches to the second-person singular sou. Jesus singles Peter out when he makes the promise: “I have prayed for you that your faith may not fail; and when you have turned again, strengthen your brethren.”
So here Jesus gives Peter alone a special pastoral role to keep the apostles united in the faith by strengthening them. In order for the apostles to benefit from Jesus’ prayer of protection in faith, then, they have to stick with him! Therefore, Peter is the visible principle of unity.
A second kind of evidence is patristic evidence. One good example is Clement of Rome’s letter to the Christians in Corinth. Clement was bishop of Rome (pope) in the second half of the first century, and the Christians in Corinth appealed to him to help settle a dispute—implying that he had a unique role in promoting Christian unity.
Ignatius of Antioch, in his letter to the Romans (~A.D. 110), describes the church in Rome as having a preeminence of some sort when he says it holds “the primacy of the community of love.” Irenaeus of Lyons, in his work Against Heresies, (~A.D. 180), teaches, “It is a matter of necessity that every Church should agree with this church [of Rome], on account of its pre-eminent authority.”
We can also look to the actions of Pope St. Victor, who reigned from A.D. 189-199. One of his acts as pope was to summon bishops throughout the world to assemble and draw up decrees to stipulate that Easter would be celebrated on Sunday. When the Asian bishops, along with their spokesman Polycrates, refused to follow Pope Victor, he threatened them with excommunication. Although Irenaeus, desiring to keep peace with the Asian churches, pleaded with Victor not to go through with it, he never once challenged Victor’s authority to excommunicate. (That power, stemming from the authority to bind and loose, is a necessary part of the pope’s role as the visible foundation of Church unity.)
A final line of evidence is evidence from reason. The simple logic of human relationships, and how we work as human beings, demands an organizational structure with a focal point of leadership in Jesus’ Church.
The religion Jesus started is not like a group of guys getting together every weekend to have pizza and beer (or in my case as a Cajun, crawfish and beer). Jesus intended his Church to be catholic, a religion that spans the entire globe. It’s unreasonable to think that Jesus would have started a worldwide religion without a visible leadership structure.
Furthermore, when we consider that Jesus brought new and public revelation, it is fitting that he would have established a centralized authority to ensure a correct understanding it. Otherwise, we would be left with diverse opinions as to the meaning of God’s revelation without the hope of being able to reach a consensus.
Jesus prays in John 17:21 that his disciples may be one as he and the Father are one. But Jesus didn’t merely wish for it to happen. He did something to ensure such unity would be possible. He gave us a principle and foundation of unity in the papacy, starting with Peter and continuing today with Pope Francis as Peter’s successor as the bishop of Rome.
This article was originally published on October 10, 2017 at www.catholic.com.