Jesus’s prayer in John 17 makes clear that the disciples are to be joyfully one in holiness, bound together in a glory the origin of which is divine, the glory of the Father and the Son. This is the Church on earth in its genesis. Now, as we follow Jesus further in this prayer, we see the Church in its growth.

“I do not ask that you take them out of the world but that you keep them from the evil one. They do not belong to the world any more than I belong to the world. Consecrate them in the truth. Your word is truth” (Jn 17:15-17). Again, Jesus’s prayer is for holiness, not escape. Jesus does not want his disciples to bury their heads in the sand, abstain from the world as if they are too pure. He wants them to be the salt of the earth, light of the world (Mt 5:13-16). The plea that his disciples will be kept from evil echoes the Lord’s Prayer.

“Consecrate them in the truth.” Some translations say “sanctify.” The plain meaning is that Jesus is praying the disciples are made holy in truth. They will be protected from the evil one insofar as they are consecrated in the truth. The truth is the “word.” The truth is Jesus. Earlier in the Gospel, Jesus said the Father had consecrated and sent him into the world (see Jn 10:36). Now he asks the same for the disciples.

“As you sent me into the world, so I sent them into the world” (Jn 17:18). Up to this point, we have witnessed the genesis of the Church, also that it is one and holy. Now we are beginning to see that it is apostolic. As earlier, note the trajectory: the Father sends the Son, then the Son sends the disciples, making them apostles. I call this the mission for glory, this movement begun within God himself but which will in time envelop all creation. Here it begins. The Father sends the Son and the Son sends the disciples; and then the disciples sent their disciples, and their disciples sent their disciples, and their disciples their disciples — all the way to you today, or whenever it was someone talked you into going to Church or introduced you to the Faith for the first time. This mission for glory, this apostolic movement stretches from the Father all the way to you.

We see it in Scripture and in history, this great movement of grace and the Spirit. As I said, this marks the true growth of the Church, at once spiritual and geographic. In the first chapter of Acts of the Apostles Jesus says that his disciples are to bear him witness in “Jerusalem, throughout Judaea and Samaria, and to the ends of the earth” (Acts 1:8). Thinking of Acts as a whole, the text begins in the city of Jerusalem but ends in Rome. That is the mission for glory, the evangelical growth of the Faith and the Church. As the Church teaches, that is why the nature of the Church is missionary, because it has its origin in the “mission of the Son and the Holy Spirit,” the final purpose of which is to welcome all people into the “communion of the Father and the Son in their Spirit of Love” (Catechism of the Catholic Church, No. 850).

“And I consecrate myself for them, so that they also may be consecrated in truth” (Jn 17:19). It is because of his talk of consecration here that this prayer is often called Jesus’s “high priestly prayer” or his “sacerdotal” prayer. As the Father consecrates Jesus, Jesus at the same time consecrates himself because he shares the Father’s divine nature. Yet it is Jesus’s humanity that is consecrated, and it is a consecration for us. That is, as we share in Christ’s humanity, we are consecrated in him, in truth. “He who consecrates and those who are being consecrated all have one origin” (Heb 2:11). Although Jesus is soon no longer to be present to them in the way they have grown accustomed, they are consecrated in him. That is, as this community of disciples becomes apostolic, they will remain one and holy. But, of course, we should remember what form such consecration takes, namely that of a cross. Talk of consecration is very close to talk of sacrifice. It was by the Cross, through his blood, we were consecrated (see Heb 13:12). Now, this matters because of what it suggests is true of our consecration, that it will be sacrificial too. Which, of course, is why the Cross will always be part of the Faith and life of the Church.

“I pray not only for them, but also for those who will believe in me through their word, so that they may all be one…” (Jn 17:20-21). Here is where we see even more explicitly the Church not only in genesis but in growth. The disciples are sent to us. If you want to know where in the Gospels Jesus literally prays for us, here you are. We are “those who will believe through their word.” But that means what Jesus desires for his disciples — that they be one, holy, apostolic — he desires also for all disciples of the future, for us too.

And this is where the rubber meets the road: “may all be one.” He prays for those who will believe through the disciples’ word, that they too may all be one — hēn. Again, to speak personally, this is why I’m so uncomfortable about our apparent comfort with Christian division. The lack of any sense of a problem with Christian division and denominationalism, the strange notion that all that matters is an individual’s personal relationship with Jesus regardless of one’s communion with others, it is indeed an easy thing to think, especially in polite company. But let us not fool ourselves by assuming this way of thinking has anything to do with the New Testament. It doesn’t. Jesus prayed for oneness. Just as his disciples are to be one as the Father and the Son are one, so too are today’s disciples. Again, long before converting to Catholicism, this is what haunted me, that Jesus wanted us to be one, but that we were not one at all.

But why is this so important? Jesus goes on: “as you, Father, are in me and I in you, that they also may be in us…” (Jn 17:21). Is it possible that our oneness as disciples is a condition of our communion with God? That, at least in this verse, the oneness of disciples seems conditionally associated with divine indwelling should serve as a deep warning about our unreflective comfort with Christian division. Our participation in God is involved in our participation with each other. How can we be divided and still comfortably assume God’s favor? Our union with each other does matter. Where two or three are gathered, we should remember, Jesus is present (see Mt 18:20). Our relationships with each other are significant to our relationship with God. Again, these are the verses that began to make me uncomfortable being content with Christian denominationalism and division. They are the verses that forced me to think of the Church like a Catholic, to think of the Church as communion, one communion, holy and apostolic.

But that is not the only reason oneness matters. Remember, Jesus is sending out his disciples for a reason: “that the world may believe that you sent me” (Jn 17:21). Supposedly Gandhi once said, “If it weren’t for Christians, I’d be a Christian.” Speaking from his experience of Christians, it was a fair point. When your experience of Christianity is of warring missionaries, when, on the one hand, you have the pope and, on the other hand, televangelists, Twitter stars, and megachurch preachers, each claiming to represent Christianity, it makes perfect sense that reasonable people would look at all these different voices and pass on Christianity, to think none of it credible or believable. It is amazing to me that more Christians do not see this. And it is also amazing to me how many Christians and Christian institutions, of all denominations, spend vast amounts of time, energy and money on evangelism and missions, tinkering with preaching, with outreach and on and on, yet very few say anything about this verse: “may they may all be one … that the world may believe.” To me, it is perfectly obvious why Christians of any stripe are having a hard time convincing people about Jesus, because our divisions have become so many and so hardened. Unity affects credibility. Jesus said so. This has always been true, and is what we have always believed.

Father Joshua J. Whitfield is pastor of St. Rita Catholic Community in Dallas and author of “The Crisis of Bad Preaching” (Ave Maria Press, $17.95) and other books. Read more from the series here.