A single Latin word—all of eight letters—has divided Eastern and Western Christianity for nearly a thousand years. The word is filioque, meaning “and the Son,” and it was added to one of Christianity’s most important statements of faith—the Nicene Creed. While it may sound like an obscure theological technicality, the controversy touches the very heart of how we understand God as Trinity. And the Reformed tradition has consistently sided with keeping this controversial addition. Let’s see why.

 

THE BACKSTORY: WHAT TRIGGERED THE CONTROVERSY

The original Nicene Creed, finalised in 381 AD, declared the Holy Spirit “proceeds from the Father.” The simple statement described the Spirit’s eternal relationship within the Trinity. But beginning in 6th-century Spain, Western churches began adding filioque—”and the Son”—so the creed now read that the Spirit “proceeds from the Father and the Son.”

Why the change? Spanish bishops were combating a heresy called Arianism, which denied Jesus was fully God. By emphasising the Spirit proceeds from both Father and Son equally, they underscored the Son’s complete divinity. The addition spread throughout Western Europe and was eventually adopted by Rome itself in the 11th century.

The problem? This change was made without calling an ecumenical council—a gathering of bishops from both East and West. To the Eastern (Orthodox) Church, this unilateral addition violated how the church had always worked: major doctrinal statements required universal agreement. The filioque controversy became one of several factors that led to the Great Schism of 1054, when Eastern and Western Christianity formally split.

 

WHY THE EAST OBJECTS

Orthodox Christians have maintained three main objections to the filioque:

• The procedural issue: They insist the West had no right to change an ecumenical creed on its own authority.
• Misrepresentation of the Trinity: Second, they argue it damages our understanding of the Trinity. In Eastern theology, the Father alone is the ultimate source and origin within the Godhead. Having two sources—Father and Son—for the Spirit’s procession disrupts this order and risks making the Trinity seem to have two separate “starting points” rather than one.
• Subtle but important linguistic differences at play. The Greek word the original creed used (ekporeusis) carries a technical meaning about ultimate origin that doesn’t map perfectly onto the Latin word (processio) that Western theologians used. What looks like a theological dispute may partly reflect different philosophical vocabularies.

Some Orthodox theologians suggest a compromise: the Spirit proceeds from the Father through the Son. This preserves the Father’s role as sole source while acknowledging the Son’s involvement.

 

THE REFORMED DEFENCE

John Calvin, the tradition’s founding theologian, addressed the filioque directly in his Institutes of the Christian Religion. He called the Orthodox objection “a petty quarrel over a word” and defended what’s called “double procession“—the teaching that the Spirit proceeds from both Father and Son together as from a single principle.

Calvin’s main argument was biblical. Jesus said the Spirit “proceeds from the Father” but also that he would “send” the Spirit and that the Spirit would “receive” from him and “take what is mine” (John 15:26; 16:14-15). Paul wrote God sent “the Spirit of his Son” into our hearts (Galatians 4:6). For Calvin, this language clearly showed the Son’s active role in the Spirit’s procession.

Other Reformers largely followed Calvin’s lead. The Belgic Confession and Westminster Standards both affirm double procession. However, these Reformation-era debates focused primarily on Rome, not Constantinople, so detailed engagement with Eastern concerns was limited.

 

WHERE REFORMED THINKERS STAND TODAY

Most contemporary Reformed theologians continue to support the filioque clause substantively. Scholars like Michael Horton and Robert Letham argue double procession best captures biblical teaching and protects the full equality of Father and Son within the Trinity.

However, a growing minority acknowledges the East’s concerns do have merit. Some suggest “through the Son” might be a better formulation—preserving the theological substance while respecting Eastern sensibilities.

Nearly all contemporary Reformed thinkers now admit adding filioque without Eastern consent was procedurally wrong, even if the theology itself is sound.

An emerging consensus recognises the millennium-old debate may involve more linguistic and cultural differences than substantive theological disagreement. Both traditions affirm the Spirit is intimately related to both Father and Son. The question is how best to express that relationship.

 

THE PATH FORWARD

In the end, the Filioque clause isn’t some dusty relic from a 1000-year-old church brawl—it’s a living heartbeat for Reformed theology. It anchors our view of the Trinity in Scripture’s clear light: the Father as the fountain, the Son as the beloved partner, and the Spirit as their unbreakable bond of love and mission (think John 15:26 or Galatians 4:6). From Calvin’s sharp pen to today’s voices, Reformed thinkers have built a rock-solid case—biblical, patristic, and practical—that honours God’s unity without tipping into the pitfalls the Orthodox rightly feared.

Sure, debates linger, and ecumenical bridges need mending. But here’s the Reformed rally cry: Lean into “and the Son.” It deepens our worship, sharpens our guard against heresies like Arianism, and invites honest talks across the aisle. As John Calvin put it so simply, “The Spirit is the bond of union between the Father and the Son.” Let’s embrace double procession not to win ancient arguments, but to deepen our worship of the triune God and engage charitably in ecumenical dialogue.

 

THE FILIOQUE CLAUSE: REFORMED SUPPORT—RELATED FAQs

Did any Church Fathers before the split teach double procession? Yes, several Western Fathers implied or taught the Spirit proceeds from both Father and Son, including Augustine of Hippo (354-430 AD), who was the most influential theologian in this development. However, Eastern Fathers like the Cappadocians emphasised the Father as the sole source, showing this theological difference existed even before it became controversial. The real issue is neither side had definitively settled the question before the addition was made.

• Are there any Protestant traditions that reject the filioque? Some Anglicans and Lutherans have reconsidered the filioque in ecumenical dialogues with Orthodox churches, with a few liturgical communities quietly dropping it from recitations of the Creed. However, these remain minority positions. The vast majority of Protestant confessions and traditions, including Reformed, Lutheran, Anglican, Methodist, and Baptist churches, affirm double procession even if they don’t always use the word filioque explicitly.
• Does this controversy actually matter for everyday Christian life? While it may seem abstract, how we understand the Spirit’s procession affects how we think about prayer, worship, and the Spirit’s work in our lives. Eastern Christians often emphasise experiencing God’s mystery and the Spirit’s freedom, while Western Christians tend to emphasise understanding God’s nature and the Spirit’s ordered relationship to Christ. These different emphases have shaped two distinct spiritualties over centuries, affecting everything from liturgy to iconography to approaches to theology itself.

What role did politics play in this controversy? Significant. The filioque dispute coincided with growing tensions between the Pope in Rome and the Patriarch in Constantinople, both claiming primacy over the church. It also reflected the political split between the Latin-speaking Western Roman Empire and the Greek-speaking Eastern Byzantine Empire. What began as a theological disagreement became entangled with questions of papal authority, imperial power, and cultural identity, making reconciliation much harder.

• Have there been any attempts at reconciliation on this issue? Yes, multiple attempts. In 1274 and again in 1439, councils tried to reunite East and West, with the filioque as a central issue, but both efforts ultimately failed. More recently, the 1995 “Clarification” from the Pontifical Council tried to explain that Catholic teaching doesn’t mean the Father and Son are two separate sources, acknowledging Eastern concerns. Many theologians on both sides now believe the disagreement is more about language and emphasis than irreconcilable theological positions.
• What does “procession” actually mean in this context? Procession describes the Spirit’s eternal relationship to the Father (and Son) within the Trinity—not something that happened in time, but something that characterises who the Spirit eternally is. It’s distinct from the Spirit being “sent” into the world at Pentecost. Think of it as describing the Spirit’s permanent identity within God’s inner life, rather than a historical event or an action God performs.

Why don’t we just remove the filioque to restore unity? It’s complicated. Many Western Christians believe removing it would suggest the theology itself was wrong, potentially undermining the Son’s full divinity—the very concern that motivated its addition. There are also practical challenges: countless confessions, hymns, and liturgies incorporate double procession theology beyond just the Creed itself. However, some theologians suggest we could keep the theology while acknowledging the Eastern formulation (“through the Son”) as equally valid, allowing different expressions of the same truth.

 

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