Why did Pope St. John XXIII call the Second Vatican Council? And what was the Council about? Taking stock of the state of theology and the life of the Church in the 20th century, one could suggest several reasons. At the end of the day, though, it should be remembered and taken seriously that John XXIII claimed the Holy Spirit’s inspiration for calling the Council. It is quite reasonable to suggest — and also helpful to remember — this: that Vatican II was the work of the Spirit.

Before exploring the answer to this question any further, though, we should admit that Vatican II, even today, evokes a wide range of emotions. Some, for instance, think Vatican II the worst thing to happen to the Church. With it came innovations and departures from the ancient faith so horrific, it’s claimed, that many have broken away or fallen away from the Church because of it. However, on the other end, others think Vatican II changed all the mean and nasty things about Catholicism, freeing modern Catholics to be good secular liberals unbothered by a primitive creed. Here, people talk about things like the “spirit of Vatican II” but without being able to tell you where in the documents of Vatican II it says exactly what they’re saying, because it turns out they’ve not really read the documents.

These, obviously, are two extreme reactions to Vatican II, found more and more on the margins of Catholic experience these days, yet still very much present in the Church. The truth of the matter, though, is that to understand Vatican II, one must accept it as an ecumenical council of the Catholic Church and that the teaching of Vatican II is expressed faithfully in the Council’s documents themselves. That is, the “spirit of Vatican II” is found in the documents themselves, read and interpreted within the communion of the Church. Thus, to understand Vatican II genuinely, as well as modern Catholicism, one must become familiar with the Council’s documents — reading them well. And you don’t have to be a theologian to do that; you just have to know how to read.

But still, what was the Council about? Speaking personally, as a former Anglican, I’ve always thought it to be significant that the Council was called on Jan. 25 — the feast of the Conversion of St. Paul. You see, this feast concludes the Week of Prayer for Christian Unity, a week in which Christians worldwide pray for the reunification of Christian believers. It was begun as the “Christian Unity Octave” by Father Paul Wattson and the Society of the Atonement just after he and other members of the society converted to Catholicism from the Episcopal Church. This “Christian Unity Octave” by the 1920s and 1930s would be celebrated all over the Catholic world; by midcentury, Protestant bodies too would join in this endeavor of prayer. And so, that John XXIII called Vatican II at this time hints at what he hoped would be a major focus of the Council — healing the unity of Christians. Remember John 17.

But, of course, there was much more to it than that. Exploring the “why” of Vatican II, one place to begin is to read John XXIII’s opening address to the Council from October 1962. “Our duty is not only to guard this precious treasure,” he said, “but to dedicate ourselves with an earnest will and without fear to that work which our era demands of us.” His hope was that the Church would offer a fresh presentation of the Catholic faith in “perfect conformity to the authentic doctrine.” Making use of modern “methods of research” and embracing “the literary forms of modern thought,” the pope wanted the Church to speak clearly to the modern world, which he made clear necessitated a rethinking. For the “substance of the ancient doctrine of the deposit of faith is one thing, and the way in which it is presented is another.” Now what John XXIII was saying is that it’s not the Faith that’s changing, but the presentation of the Faith. He said the Church must think about the delivery of the Faith, finding ways to articulate the Faith in a reasonable, sophisticated manner that is neither fideism nor fundamentalism. John XXIII had a great deal of trust in the reasonableness of faith. The Church wasn’t meant to retreat from the world; quite the contrary. The Council’s task was to take the deposit of faith and deliver it to the world in an authentic way, without intellectual cowardice or bravado but, he said, in a “predominantly pastoral” way. That is, Vatican II wasn’t primarily about articulating theology or doctrine — as, say, in the Council of Nicaea when the fathers articulated the divinity of Christ (homoousios) — but about the pastoral articulation of the Faith.

One feature, different from other ecumenical councils, indicating this new pastoral approach is that Vatican II communicated in an entirely new idiom. It promulgated no disciplinary canons, for example, although it did inaugurate the revision of the Code of Canon Law that would come to fruition in 1983. Vatican II pronounced no anathemas as did the Council of Trent. The tone of the documents of Vatican II are completely different. They are persuasive and evocative — conversational. That is, the texts are dialogical. Gaudium et spes — the Council’s Pastoral Constitution on the Church in the Modern World — for example, reads like an invitation to the world to talk about truth, goodness and peace. It’s a profoundly hopeful and open document, not defensive or condemning.

John O’Malley’s indispensable book on the Council, “What Happened at Vatican II,” notes the common characteristics of Vatican II summed up in three concepts — aggiornamento, the development of doctrine and ressourcement. The first idea, and the one associated most readily with Vatican II is aggiornamento, which can mean “updating” or “refreshing.” It means something like what John XXIII meant when he said he wanted to “open the windows of the Church and let some fresh air in.” It’s what he talked about in his opening address — not changing the Faith at all but refreshing it, updating it.

The other characteristic of Vatican II — the development of doctrine — is an idea associated with the work of St. John Henry Newman, who is in a sense one of the intellectual fathers of Vatican II. He wasn’t present at the Council. He had been dead for 70 years by the time it began. One of the most famous modern converts to Catholicism — from the Church of England — he was a great theologian and man of letters. His book, “An Essay on the Development of Christian Doctrine,” which he wrote while still in the process of converting to Catholicism, made a simple but profound observation about the Christian faith. And that is — although there is the deposit of faith, revealed truth from Scripture and the Holy Spirit — the articulation of the faith develops over time. Now this idea for many was and remains controversial. Fundamentalists, of course, hate it. Many Eastern Orthodox theologians don’t much care for it either. But Newman’s point was basically this: Christian doctrine is sharpened, better articulated, and is expressed more clearly as it needs to be over time. Take, for example, the dogma of the Trinity. We believe that God is Father, Son and Holy Spirit. However, that dogma wasn’t fully articulated until 381. Why? Because, as Newman pointed out, there wasn’t any reason to articulate it fully until a fight broke out about it. The Church articulated definitively the full divinity of Christ only when Arius started causing trouble by questioning it. And after Nicaea, people were questioning the divinity of the Holy Spirit — they were called pneumatomachians, meaning “Spirit-fighters” — forcing the Church to articulate more clearly her belief in the Holy Spirit. And so, as history progresses, doctrine is better articulated. That’s what Newman meant by “development,” and it was an idea fundamental to Vatican II.

The last concept intrinsic to council, ressourcement, came about from around the turn of the 20th century, among theologians mainly in France who started doing theology in a new way. This new way — associated with Jesuits like Henri de Lubac and Gaston Fessard and Dominicans such as Marie-Dominique Chenu and Yves Congar — came to be called nouvelle théologie. But it was a way of doing theology that really wasn’t new at all; it was just different for its time. Sarah Shortall’s book, “Soldiers of God in a Secular World,” tells the story of this important theological movement. Neo-Scholasticism dominated theology in the 19th and early 20th centuries, and that was theology done propositionally, so to speak. That is, one defined terms and logically placed one’s propositions in logical order. The theologians of this nouvelle théologie, however, were committed to ressourcement, which simply means “return to the sources.” To understand the deposit of the faith and to articulate it theologically, these theologians went back to Scripture and to the early Fathers of the Church. Essentially, their method was this: If you want to know something about the Eucharist — for instance, transubstantiation — how should you study it? Well, you begin with the sources, with the Eucharist as it’s treated in Scripture. Then you explore what the early theologians believed and taught; then study the eucharistic controversies of the 10th century, and so on. By that method, exploring the sources of the Christian faith, a person can better understand what the Church means when it uses the word “transubstantiation.” And that’s better than simply taking a word and defining it in unhistorical abstraction — like “transubstantiation is X.” You see the difference? Ressourcement is a return to the sources that better helps us understand how ideas took shape within history. And it was a new way of doing theology in the first half of the 20th century, and one which shaped not just Vatican II but the whole of modern 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.