To belong to the Church is to belong to a communion the measure of which is nothing less than the whole of creation — the Church cosmic. And belonging to the Church opens up a new moral horizon. To believe in Christ and belong to the Church doesn’t just change the way one views history and the universe, it changes one’s understanding of moral possibility. It changes the way believers see themselves and other people — the good and the purpose of people.

As Paul said, each believer’s life is “hidden with Christ in God” (Col 3:3). That is, there’s a truth about each believer that is not visible but which is discerned only in faith. And the ethical change this effects is that now believers must measure their behavior in terms of heaven — our destiny as Ephesians puts it (Eph 1:11). Believers change their moral behavior in light of the understanding that they will live forever with their brothers and sisters in heaven.

We can think about how heaven changes morality in this way: Imagine you’re on the way to a party, but running a bit late. Flustered to begin with, on the highway you come upon a very slow driver, too clueless to get out of your way. Angry, you honk the horn and ride the driver’s bumper until finally you can pass. For good measure, as you whiz by, perhaps you give the slow driver a universally recognized hand gesture just to make sure he or she understands your displeasure. But now imagine, 10 minutes later, you arrive at the party. You park and look in the rearview mirror to see the slow car parking just behind you. You both get out and walk to the door, as you begin to feel faint, realizing that you’re going to the same party. Awkward, don’t you think? Surely, if you had known that this slow driver was going to the same party as you — or let’s say, to the same heaven as you — don’t you think you would have changed your behavior on the road? Now, to make the point theologically: eschatology influences morality. When a believer genuinely realizes that his or her life is hidden with Christ in God — that Christ in heaven is his or her destination and that his or her brothers and sisters are going there too — behavior changes. And that’s how the Church cosmic gives shape to the Church moral.

But what does the morality of Christians look like? Again, we deal more thoroughly with this topic later. Here it suffices to say that believers live together in Christ, living as Christ to one another as Paul described in his Letter to the Philippians. “Complete my joy,” Paul writes — just like Jesus and John — “by being of the same mind, with the same love, united in heart, thinking one thing” (Phil 2:2). It’s almost as if Paul may have read John 17.

What is the task of Christian people? To be one. How do we do that? By being like Christ to one another. Forsake rivalry, be humble, count others more important than yourself. Such humility, patterned on Christ, was something utterly new in moral thinking. Aristotle would’ve considered what Paul is recommending simply a form of dishonesty. If one is a great man, Aristotle thought — and, by the way, only a man could be great in his mind — then one should acknowledge it and strive to be what he called “magnanimous.” Jesus, though, gave believers another model. He was indeed great — in the “form of God,” Paul said — but yet he “emptied himself, taking the form of a slave” (Phil 2:6-7). He lowered himself to serve and save others. And because of this — because he rose from the dead and is now exalted as Lord — now everyone can be great, not just Athenian men — even those deemed lowest, those on the farthest margins of society. This radically changed society. This new moral example — the example of Jesus Christ — inspired Christians to practice humility, which ideally is the ethic of all believers, of the entire Church, for it’s how believers remain one and how they show Christ to each other and to the world. They practice humility because they believe Christ is Lord of heaven and earth, because their moral horizon now extends well beyond earthly life.

And it’s a way of life that has consequences, as John made clear. “Do not be amazed if the world hates you,” he wrote (1 Jn 3:13). Jesus, of course, said the same thing (Jn 15:18-25). The way believers live their lives is at times radically different than the way others live theirs. And, just as the way Jesus lived his life convicted and provoked others, so too will believers sometimes convict and provoke the people around them. But that, of course, doesn’t ultimately matter; by no means does the hatred of the world destroy this new way of life lived by believers. Again, because believers know they’ve entered a new and very different world, even as they remain in the old world. Remember when Jesus said he was no longer in the world? (Jn 17:11). John put it in terms of death and life and hatred and love. “We know that we have passed from death to life,” he wrote, “because we love our brothers” (1 Jn 3:14). The ethical fruit of belonging to the Church — not just sacramentally, but morally, too — is mutual love, love that endures often alone in a world that’s forgotten love. To belong to the Church, to be one and to love each other is to experience the beginning of resurrection, eternal life, heaven. Again, we see here how the cosmic shapes the moral; passing from death to life, believers love differently — with an eternal perspective.

And again, notice the Church. As John said, this love is love for the “brothers.” Obviously, this includes women. The point is to notice that the love John is talking about isn’t some disembodied abstract love; it’s not mere feeling or attitude. The love John is talking about is fully ecclesial. That is, by love, John also means the communion of the Church. As Paul said, belonging to the “body of Christ” (another image of the Church), believers are “parts of one another” (Rom 12:5). To belong to the Christ is to belong to each other, which is to belong to the apostolic Church, an actual, tangible body of people discernible throughout history. The Church is not some abstract paradigm or disembodied ethic. Rather, it’s an organic communion of believers in Christ constituted by the gift of the Holy Spirit. We can reach out and touch it; we can see the Church. It’s not just an idea. This is an essential claim of Catholicism.

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.