Throughout its history, the Church has insisted upon its visibility.

Especially in these latter centuries as the Church — visible for so many years as some strange political entity — has changed its aspect, it has nonetheless still insisted that it is not just an immaterial, invisible society. It is, rather, quite visible. The Church is hierarchical and charismatic; it is an incarnate thing, visible and ethical, obedient to the teachings of Jesus. Echoing the Sermon on the Mount, it’s a “communion of life, charity and truth” that is “sent forth into the whole world as the light of the world and the salt of the earth” (LG 9; Mt 5:13-16). One simply can’t define the Church only in material terms or only in spiritual terms, opposing matter and spirit so absolutely. That is actually heresy.

Rather, as Lumen Gentium teaches, the Church is an “entity with visible delineation.” The risen Christ “continually sustains here on earth His holy Church,” not just as a Mystical Body, but also as a “society structured with hierarchical organs.” The “visible assembly and the spiritual community” are not to be thought of as “two realities” but as “one complex reality which coalesces from a divine and human element.” Again, the applicable analogy here is the incarnation: the idea of the divine and human present in the mysterious and visible (LG 8). Thus, the visible and material aspect of the Church cannot be completely separated from its invisible spiritual reality. That the Church is always visible simply follows from the fact of its nature as sacrament. This is basic Catholic theology, shared though also by the Orthodox and many other Christian traditions.

It’s at this point, however, we encounter some of the unique claims of Roman Catholicism. Simply put, how does this Church we’ve been describing since John 17 relate to the Roman Catholic Church? The answer is complicated. Thus, Lumen Gentium speaks here carefully: “This Church constituted and organized in the world as a society, subsists in the Catholic Church, which is governed by the successor of Peter and by the Bishops in communion with him, although many elements of sanctification and of truth are found outside of its visible structure. These elements, as gifts belonging to the Church of Christ, are forces impelling toward catholic unity” (LG 8).

Now, this is a loaded paragraph! As we’ve already seen, the Church, as sacrament, is a visible organism — hierarchic, charismatic, spiritual, material — but not entirely circumscribable. That is, the Church we’ve been describing since John 17 is not exclusively identifiable with the Roman Catholic Church. The Church is bigger, more mysterious than that. But still, in a very real sense, the Roman Catholic Church is the Church. So, how do you get your head around that?

Lumen Gentium teaches that the Church “subsists in” the Catholic Church — the Church governed by the successor of Peter. Now, this little Latin verb — subsistit — is probably the most controversial word ever to come out of Vatican II. It does indeed mark a change in how the Catholic Church describes itself in relation to other Christian bodies, but it needn’t be controversial. Before the Second Vatican Council, most Catholic theologians were content simply to say that the Church is(est) the Roman Catholic Church. However, Lumen Gentium changed that, adding actually quite helpful nuance. By saying the Church “subsists in” the Roman Catholic Church, Lumen Gentium is not saying the Roman Catholic Church is the ideal Church or the real Church in the sense that other Christian communities are unreal; rather, it’s saying that the Church described in the New Testament is always fully present in the Roman Catholic Church, that by its sacraments and apostolic and Petrine structure, the oneness Jesus prayed for in John 17 is never absent from it (Unitatis Redintegratio, 4). It’s saying that the Roman Catholic Church, ecclesiologically speaking, will always be fully and substantially the Church described in the New Testament and throughout Christian history.

But what about those churches and communities not part of the Roman Catholic Church? What about non-Roman Catholics? The Second Vatican Council teaches that the Christian Church subsists in the Roman Catholic Church, the Church in communion with Peter and his successors, the popes. And yes, it also teaches that non-Roman Catholic churches and communities are different from the Roman Catholic Church, that they “are not blessed with that unity which Jesus Christ wished to bestow on all those to whom he has given new birth into one body … that unity which the Holy Scriptures and the ancient Tradition of the Church proclaim” (Unitatis Redintegratio, 3). However, non-Roman Catholic churches and communities do indeed possess “many elements of sanctification” and also many gifts belonging to the great Church of Christ, all of which are innately “forces impelling toward catholic unity” (LG 2.8). Thus, for Baptists, Methodists, Anglicans, and so on — anyone with an inkling for truth: such truth, in whatever community it flourishes, tends toward the perfect unity of the Father, Son, and Holy Spirit given to the Church in Christ.

But how can we get our heads around this very bold claim? The image that helps me think about this is a simple one — a broken flower pot. If I dropped a big potted plant on the floor, breaking it into several pieces, and if I looked at you and said, “Pick up the plant” — what would you do? You’d likely pick up the root stock, the big bit. It’s unlikely you’d pick up that smaller fragment off to the side or the even smaller one farther away. When I say, “Pick up the plant,” you’re going to pick up the part you know is more fully the plant. But, of course, all the pieces belong together. All the fragments matter. That’s what Lumen Gentium means when it says the Church “subsists in” the Roman Catholic Church. The one fragment off to the side may be Baptists with their great preaching; another fragment, Anglicans with their beauty and humor; another, Methodists with their hymnody. You see what I’m saying? That’s basically the idea. All the broken pieces belong together, but the fullness of the thing is what it is — the Roman Catholic Church.

That’s the unique claim of Roman Catholicism; and undoubtedly, it’s quite a claim. Speaking personally as a convert, I had to explore and wrestle with this for quite some time. I understood that Jesus meant us to be one; and I also understood (as we’ll explore later in this series) that being one meant being one eucharistically, visible one. But does that therefore mean Roman Catholicism? I mean, I had been around Roman Catholics and was not bowled over. And so, for me, it became a historical investigation, questions regarding the claims of the papacy. Is it true, for instance, that all Christians should be in communion with Peter and his successor? I did indeed come to believe this, yes. At this point, suffice it to say that I had to come to grips with this theology, and it wasn’t easy. But in the end, my accepting it stemmed from this idea of God’s mission for glory — that the Father sent his Son and that through the Son and the Spirit, the Church was created in holy, catholic, and apostolic oneness, a divine and human communion. Now indeed, this is an outstanding claim the Roman Catholic Church makes for itself. Yet, like it or lump it, believe it or not, for twenty centuries the Church has found the guts to proclaim it in season and out. Disagree, that’s fine — it’s understandable and even respectable in some instances. But, nonetheless, the outstanding claim remains; there it is. The Church we’ve been following since John 17 “subsists in” the Roman Catholic Church. It was the blunt stubbornness of this teaching that made me wrestle with it so much. Which really is all I can say to you — wrestle with it. Because this is what we Catholics really believe.

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.