If you had to list the greatest theological controversies in the history of the church, which would you choose?

Perhaps we remember learning about Athanasius’s battle against the Arians for the divinity of Christ. From there, we might recall Augustine’s dispute with Pelagius concerning our sin and God’s grace. Eventually, of course, we would make our way to the Reformers’ conflict with Rome over justification, among other matters. Perhaps only a few of us, however, would think to mention another event as massive, in some ways, as the Reformation itself.

Nearly five hundred years before Luther placed his 95 theses on the door of Wittenberg’s Castle Church, a Catholic cardinal named Humbert placed a sentence of excommunication in the cathedral of Hagia Sophia in Constantinople (modern-day Istanbul). Michael Cerularius, the patriarch of Constantinople and recipient of the sentence, promptly excommunicated Humbert in return. The exchange — sometimes called the Schism of 1054 — eventually left the one holy, catholic, and apostolic church torn in two: East and West, Orthodox and Catholics.

What was the cause? Eastern and Western Christians had wrangled for centuries over a host of issues, from the authority of the pope to the celibacy of priests. But behind these grievances stood one far larger, even though it rested on a single Latin word: filioque. That one word represents the greatest theological controversy most Protestants have never heard of.

Brief History of the Filioque

The meaning of the word filioque may seem, at first, to be less than controversial: it simply means “and the Son.” Controversy begins to swirl, however, when you ask whether the word filioque should be part of the Nicene Creed (officially known as the Niceno-Constantinopolitan Creed). In the original version of the creed, which dates to 381, the section on the Holy Spirit begins,

We believe in the Holy Spirit, the Lord and Giver of life, who proceeds from the Father.

Over time, however, some Christians in the West altered the sentence to read,

We believe in the Holy Spirit, the Lord and Giver of life, who proceeds from the Father and the Son.

“And the Son” — filioque. A brief look at the history of the controversy will reveal why such a seemingly innocuous word could tear apart the visible church.

Western Addition

As far as we know, the word filioque first appeared in the Nicene Creed at the Spanish council of Toledo in 589. Scholars disagree on why the council altered the creed, but many think the Spanish church wanted to oust the Arians in the region, who denied the deity of the Son. By asserting that the Spirit proceeds from the Father and the Son together, the council confessed the Son’s equality with the Father in a way that left less room for Arian evasions.

Although the word filioque had not appeared in the Nicene Creed until Toledo, the concept of the filioque was not new — at least in the West. A century and a half earlier, the great Augustine had written in his book On the Trinity,

Neither can we say that the Holy Spirit does not proceed also from the Son, for the same Spirit is not without reason said to be the Spirit both of the Father and of the Son . . . the Holy Spirit proceeds from the Father and from the Son. (Macleod, The Person of Christ, 143)

In view of such a clear teaching from a pillar of the Western church, the members of the council may have thought they were simply clarifying the meaning of the creed along agreed-upon Augustinian lines.

At the time, the decision in Toledo created barely a stir. Being local, the council did not speak for the whole church, nor even the whole Western church. Over the next two centuries, however, the popularity of the filioque grew in the West until, in 809, the Roman Emperor Charlemagne put his imperial authority behind it. The pope at the time, Leo III, agreed theologically but resisted the idea of altering an ecumenical creed. But by the early eleventh century, the papacy approved, and the filioque became engraved in all the creeds of the West.

Not, however, in the East.

Eastern Objection

While Spanish Christians met in Toledo, and Charlemagne ruled the West, and the papacy finally put its pen to the Nicene Creed, the East found itself on a different trajectory entirely. Neither the word nor the concept of the filioque was taught in the East, nor had their Trinitarian thought followed the steps of Augustine. When the filioque finally found its way to the East, then, the churches refused to embrace it.

Robert Letham notes two principal objections the East leveled against the filioque. The first was ecclesiastical, since “such a change . . . should require an ecumenical council akin to Nicaea, Constantinople and Chalcedon” (Through Western Eyes, 225). By its very nature, an ecumenical creed must be altered ecumenically — the whole church must be represented.

The second and more important objection was theological. Despite the East’s wholehearted sympathy with the West against the Arians, they were not willing to place the Son alongside the Father in the Spirit’s procession. In fact, three hundred years after Augustine argued for a double procession of the Spirit, the East’s John of Damascus taught just the opposite: “We speak also of the Spirit of the Son, not as though proceeding from him, but as proceeding through him from the Father. For the Father alone is cause” (Macleod, The Person of Christ, 143).

The East held to such a position, in part, because its Trinitarian theology differed from the West’s. According to Augustine and the West, writes Gerald Bray, “the Holy Spirit is the mutual love of the Father and the Son,” and therefore “he stands in the same relationship to both” (God Has Spoken, 649). According to the East, however, “Since the Son and the Father are not the same, their respective relations to the Holy Spirit cannot be the same either. Therefore to talk of the Spirit proceeding from the Father and the Son without differentiation is to confuse the two” (Through Western Eyes, 230).

For a thousand years, the Eastern and Western churches remained in fellowship, despite speaking different languages and living in different cultures. But now, the filioque brought the fault lines, long buried, to the surface.

Schism of 1054

When the tensions between East and West finally led to the showdown in Hagia Sophia between Cardinal Humbert and Michael Cerularius, the filioque was not at the heart of the dispute. Nor was Humbert’s and Cerularius’s quarrel the only grievance that finally separated East from West. Just as decisive, and perhaps more so, were the crusaders from the West, who set up rival bishops in the East and, in 1204, plundered Constantinople.

Nevertheless, the mutual excommunications of 1054 formed a breach that, to this day, has not been repaired. And all attempts at reunion throughout the last millennium have foundered, again and again, on this one rock: filioque.

Of particular importance is the Council of Ferrara-Florence in the mid-fifteenth century, where disagreements over the filioque caused the rift to widen into a gulf. In the aftermath of the council, the East’s Mark Eugenicus wrote of filioque sympathizers, “Avoid them and their fellowship. They are ‘false apostles, deceitful workmen, disguising themselves as apostles of Christ’ [2 Corinthians 11:13]” (God Has Spoken, 707). “In such a climate,” Bray writes,

the Filioque stood no chance, and since then the rejection of it has been a hallmark of allegiance to Eastern Orthodoxy, a badge of belonging that cannot be surrendered without incurring the charge of apostasy from the true faith. (707)

Even today, before Catholics can convert to Orthodoxy, they must renounce, among other teachings, the doctrine of the filioque (Through Western Eyes, 249).

Three Takeaways for Protestants

Historically, while Orthodox and Catholics have been embroiled in debate over the filioque, Protestants have taken little interest. Of course, Protestants, in name, weren’t even around until five centuries after the Schism of 1054. But even the Reformers, who were not afraid to challenge Rome, for the most part adopted the Western position without extensive comment.

Modern Protestants have even less interest. Bray writes, “When an issue like the Filioque is raised today, it often meets with a mixture of incomprehension and impatience. Cannot such an obscure point be resolved or simply ignored?” (God Has Spoken, 709).

Before we answer yes, we might consider how Protestants can reflect and respond profitably to the filioque controversy in at least three ways. First, we can acknowledge the debate’s complexity. Second, we can appreciate the family history, especially of Eastern Orthodoxy. And third, we can begin to enjoy the Trinity more deeply.

1. Acknowledge the complexity.

Some Protestants, hearing about the filioque controversy for the first time, may wonder why there’s a debate at all. They see in Scripture that Jesus sends the Spirit (John 15:26), Jesus breathes the Spirit (John 20:22), and the Spirit is called “the Spirit of Christ” (Romans 8:9). Surely, then, the Spirit proceeds from the Father and the Son? But matters are not quite so simple.

For example, Eastern Christians observe that, in John 15:26 (a key verse in the debate), the verbs describing the Spirit’s relationship between the Father and the Son are different: the Spirit proceeds from the Father; he is sent by the Son. Nick Needham, a Protestant who holds the Eastern view, asks,

Could we not say that the Holy Spirit is the Spirit of the Father by original possession, and the Spirit of the Son by an eternal proceeding of the Spirit to the Son from the Father, so that from all eternity the Spirit rests on the Son and abides in him — that the Son is the eternal abode, the timeless holy temple, of his Father’s Spirit? (“The Filioque Clause” in Scottish Bulletin of Evangelical Theology 15/2, 155)

Such a proposal seems to satisfy much of the language of Scripture. Jesus sends the Spirit and breathes the Spirit because he has, from all eternity, received the Spirit from the Father.

This is not to say that the Reformers were misguided to retain the filioque in the Protestant tradition. They had their reasons for believing the Spirit proceeds from both the Father and the Son, as do most Protestant theologians today. This is simply to say that the issue is complex and that the Eastern view has more to commend it than we may at first observe. Perhaps the best stance for many of us, especially the non-theologians among us, is that of J.C. Ryle:

It must be honestly conceded that the Scripture does not so distinctly and directly assert [the procession from the Son] as the procession from the Father. . . . The difference between the Eastern and Western Churches may after all be more apparent than real; and we must beware of denouncing men as heretics, whom perhaps God has received. (Expository Thoughts on the Gospel of John, 3:128)

2. Appreciate the family history.

The filioque controversy forces into view a branch of the Christian church that is, for Protestants at least, easily forgotten: Eastern Orthodoxy.

Protestants who explore the Eastern Church may feel, at first, like Orthodoxy is even more foreign than Catholicism. When we walk into the world of the Orthodox, we enter a world of icons and liturgies, of patriarchs and bishops, of apophatic theology and deification. Letham likens the experience to meeting a long-lost cousin with a different accent and a face you barely recognize.

Nevertheless, the more we look at Eastern Orthodoxy, the more we find roots of our own family history. For Protestantism rests, in part, upon the ancestors of today’s Eastern Orthodox. It was the Greek-speaking East that gave us Athanasius, Basil the Great, Gregory of Nyssa, Gregory Nazianzen, and John Chrysostom — champions and heralds in the household of God. These men, and others, hammered away at heresy and protected orthodoxy in the church’s first ecumenical councils, to which Protestants happily subscribe.

No doubt, many differences in theology and practice divide today’s Protestants and Orthodox, some of them profound and concerning. But we ought not allow these differences to keep us from the history that holds so much of our heritage.

3. Enjoy the Trinity.

While we learn about the Orthodox, we may even find ourselves going one step further and learning something from them. And one area where Protestants can learn from the Orthodox is in their lived experience of the Trinity.

For the Orthodox, as the filioque controversy illustrates, the doctrine of the Trinity does not sit on the sidelines of faith. It is not merely a chapter in a systematic theology textbook, and it is certainly not a mathematical puzzle. The Trinity is, rather, the heart of Christian faith, the happiness of the saints, and the only hope of our salvation.

Protestants may indeed wonder whether East and West placed too much freight in that one Latin word filioque, but we ought to do so only after a long look inward, wondering if perhaps we Protestants have placed too little freight (perhaps none at all) in the doctrines that describe our God.

If we want to move toward a deeper experience and enjoyment of the Trinity, we need not travel east. We have, in our own tradition, all the kindling we need to enjoy a personal awakening to the glory of Father, Son, and Spirit. Not only old books, like John Owen’s Communion with God, but also new ones, such as Fred Sanders’s The Deep Things of God and Michael Reeves’s Delighting in the Trinity, lay out a feast of Trinitarian enjoyment.

In the last of these, Reeves writes, “To know the Trinity is to know God, an eternal and personal God of infinite beauty, interest and fascination. . . . What we assume would be a dull or peculiar irrelevance turns out to be the source of all that is good in Christianity. Neither a problem nor a technicality, the triune being of God is the vital oxygen of Christian life and joy” (Delighting in the Trinity, 12, 18).

Many of our fathers in the faith thought about the filioque not because they were enamored with doctrinal subtleties, but because they were enamored with the Trinity. We ought to follow them — not necessarily into the controversy, but certainly into the enjoyment.