The unity of the Church is one of the great misunderstood notions of history. This is understandable because the unity of the Church is not a human idea but a mystery of revelation — one almost as profound as the mystery of the Blessed Trinity.

Many modern people are sure they have a quick and easy understanding of the unity of the Church.

Not a few people have a notion of the Church as “what the apostles cooked up to occupy their time after Jesus departed the scene.” That’s why so many people speak of the Church as a “mere human institution.”

If they are unbelievers, this human institution is generally seen as a fellowship of liars or deluded fools.

If they are believers, they often see the Church as a bunch of people who are well-meaning followers of Jesus, but not as a divine institution possessing a superhuman unity.

Many believers fancy unity is based on human effort, so they imagine that unity consists of Christians all agreeing with each other in a monolithic fashion and doing the same stuff.

Since a bare glance at the Christian world confirms that this seldom occurs, many people therefore conclude that the unity of the Church is an “ideal” that is virtually never achieved and, in real life, probably shouldn’t be achieved.

That’s why the Catholic Church is constantly being berated as “totalitarian” or “authoritarian” by its critics. Though there is sometimes a sentimental attachment to “once upon a time unity” (“Way back when, during the New Testament, believers were all in one accord …”) the fear is that “unity” in real life today means having your individuality digested by a sort of collective in which all drones think, talk and do the same.

In this view, the unity of the Church is a sort of self-hypnotic mass achievement of its members: a terrifying destruction of the distinctiveness of the person for the sake of the hive.

But the startling truth is this: The unity of the Church is not based on our achievements any more than our salvation is. The unity of the Church, like the holiness of the Church, is a metaphysical reality that exists now, whether we realize it or not and whether we like it or not.

That’s because the Church, unlike any merely human society, is the only organization that exists before it has any members.

The Church is the body of Christ, who is its head. It is he therefore — not we — who is the guarantor of its unity just as he is the guarantor of its holiness.

His Spirit is the soul of the Church and it is his Spirit that holds the whole thing together and makes it holy, not our personal goodness or intellectual integrity.

The fact that Christ, and not we, is the basis and guarantor of the Church’s unity does not mean that we can just coast or do whatever we like.

Paul urges the Ephesians to “lead a life worthy of the calling to which you have been called, with all lowliness and meekness, with patience, forbearing one another in love, eager to maintain the unity of the Spirit in the bond of peace” (Ephesians 4:1-3).

We can, of course, break with the unity of the Church by heresy or schism. But that does not mean the unity of the Church breaks. It merely means that we break with the unity of the Church.

When we sin against the unity of the Church by heresy or schism, we break something in ourselves. But the unity of the Church remains — albeit wounded. For it is Christ, not us, who constitutes the unity of the Church.

The really interesting thing, however, is not that we can break with the unity of the Church through sin. It’s that we can be partners with Christ in maintaining it. And the really interesting thing is how Paul says we do that.

The essence of Paul’s moral teaching is not “Follow this list of rules.” His instruction boils down to this: “Become who you are.” That’s what he’s saying in the passage above.

In other words, he’s saying that Christ is the essential thing, the basis and guarantor of the Church’s unity.

Now that you are in Christ through baptism and the other sacraments, stay put, imitate him, and the unity of the Church will happen in and through you because Christ cannot contradict himself. That’s a whole different world from rules and regulations, consensus building, group therapy, collectivization or the various other schemes we humans have concocted over the years in the quest for unity.

It’s also, by the way, the only thing that will ultimately last and give us both the loving union with God and others and the personal freedom our souls crave.

Next week: In Doubtful Things, Liberty.

Mark Shea is content editor

at CatholicExchange.com.