We Protestants—heirs of the Reformation—are sadly accustomed to church splits. So it’s hard for us to fathom the significance of the massive schism of 1054 when the Eastern Church broke from the West. The division between the Western Church (which now includes Roman Catholicism and Protestantism) and Eastern Orthodoxy wasn’t caused by debates over the deity of Christ or, even, justification by faith. It was over something much more subtle; something we call the filioque clause.

You may be familiar with this debate and find it trivial. Still more of you probably have little idea what I’m talking about. But I am convinced this debate does matter, especially for Protestant pastors. So let me give a very brief summary, just in case you’re a little fuzzy or completely unaware of the details, and then argue a case for why it matters for pastors. While there are lots of juicy political details and ecclesiological baggage in the story, I’ll stick mainly with the theological bits.

The Filioque and the Authority of Scripture

From the early Nicene and Constantinopolitan creeds, the confession of the Holy Spirit read like this: “the Lord, the Giver of Life, who proceeds from the Father.” The Spirit proceeded only from the Father, not the Son. Now, we’re not certain exactly when, but eventually the West added a phrase: “the Lord, the Giver of Life, who proceeds from the Father and the Son.” (The Latin word, filioque, means “and the Son.”) This confessional move to add “and the Son” was condemned in the East by Patriarch Photius I of Constantinople (right) in 864.

This variance became a way in which the East and West distinguished themselves on the missionary front, also bringing with it much political tension. The West officially adopted the amended creed in 1014, leading the East to officially split in 1054.

This debate might not feel so consequential as the debate over justification by faith alone, for example. But it carries great historical import, because in the filioque controversy we can cite an example when the authority of Scripture trumped the authority of councils. Some may push back and say that it was all a political game. Roman Catholics can argue that nothing was official until the pope stepped in, so really the authority of the church triumphed. But in the end, it was pastors and theologians grappling with their Bibles to explain, not only God’s self-revelation, but also how God is involved in redeeming and sustaining his people.

I don’t mean to undermine the importance of creeds or the work of the church councils. The first seven councils are a good judge of Christian orthodoxy, and we can hold them up as a standard for biblical Christianity that we should be very slow to challenge. But their conclusions are accountable to God’s Word. And it’s here, in the filioque controversy, where Protestant pastors—indeed, every Christian who takes seriously the final authority of the Bible—can find a good example, political struggles aside, of the church laboring to be true to God’s Word.

Evidence for the Filioque Clause

Just because a historical event gives credence to the Protestant cause doesn’t mean it’s legitimate. Still, I think the Bible gives us every reason to believe that the filioque clause accurately reflects God’s work and Word.

The Upper Room Discourse in John’s Gospel is the most obvious place to start, where Jesus spends a good bit of time talking about the “sending of the Spirit.” In John 15:26, the Son sends the Spirit, “who proceeds from the Father.” Also, in John 16, Jesus comforts his disciples saying, “it is to your advantage that I go away, for if I do not go away, the Helper will not come to you. But if I go, I will send him to you” (John 16:7, emphasis mine). Several other passages (John 16:13-15; 15:26; 14:26; Mt. 3:16; cf. Mk. 1:10; Lk. 3:22) give us a more complex picture of the relationship of the Father, the Son, and of the Spirit than the Eastern Church offers. Robert Letham comments on this complexity:

The Holy Spirit hears the Father, receives from the Father, takes from the Son and makes it known to the church, proceeds from the Father, is sent by the Father in the name of the Son, is sent by the Son from the Father, rests on the Son, speaks of the Son, and glorifies the Son.

Some have responded in saying that how God reveals himself in human history is not necessarily a true picture of his eternal reality. But if God’s self-revelation does not indicate who he is in reality, then we are left to speculate in our search for true knowledge of God and the authority of Scripture is undermined. It’s here, again, where the authority of Scripture comes to the forefront. If the Bible can’t give us true knowledge about God, then we have a bigger problem than a church schism.

But the Bible is a reliable source of our knowledge of God, and the language it uses about God gives us insight into who he is. And when the New Testament speaks of the Holy Spirit as the Spirit of Christ, not just the Spirit of God, it is telling us something important about how the Person of the Spirit relates to the Person of the Son (Rom. 8:9; 1 Pet. 1:11). It is Christ who baptizes with the Holy Spirit (Matt. 3:11; Acts 1:5; Acts 11:16). It is Christ who promises and sends the Spirit as the One who now mediates Christ’s active presence in the world. This becomes evidentially clear in the book of Acts, where the Spirit empowers the early Christians to be witnesses of Christ to the ends of the earth (Acts 1:8), and it is through the Spirit that Christ is with them to the end of the age (Matt. 28:20).

The Filioque for Preaching and Discipleship

At this point we can begin to recognize the importance of the filioque clause for preaching and discipleship. Church leaders not only pray that their people will be more holy, but that they will be conformed to the image of Christ (Rom. 8:9; 1 Cor. 3:18, 15:49). So Paul can say that if you have the Spirit of Christ in you, then you have Christ himself in you (Rom. 8:9-10). And if we have the Spirit of Christ, then we will be conformed to his image, since the Spirit is the power of the Father, who raised Christ from the dead. And this resurrecting Spirit not only gives us new life and makes us holy like Christ, but he is also the hope of our physical resurrection when Christ returns in power (Rom. 8:10-11). For Christians who desire to make Christ the center of God’s redeeming activity, the filioque clause does a nice job of emphasizing that point from Scripture.

When I say that this issue is important for preaching and discipleship, I don’t mean that it needs to be the subject of our preaching and discipleship. That, I think, would be foolish. But what I do mean to say is that we should labor to understand God by how he reveals himself in Scripture. It should inform our prayers and inform how we talk about God’s active presence in the life of his children. It bears on how we talk about holiness and how pastors and leaders should call people to godliness. When we hear the words, “Be holy as I am holy” (Lev. 11:44; 1 Pet. 1:16; see also Matt. 5:48), it takes on a richer meaning when it is the Spirit of Christ who dwells in us and empowers us to do so.

Without this view of the filioque clause, I don’t think we have as clear of an understanding of the Spirit’s work and role in the life of believers; nor do I think we have as much certainty about the being of God.

My fear is that the reason pastors and theologians don’t talk much about the filioque clause is because they don’t talk much about the Trinity at all. As Carl Trueman has often put it, our churches may believe in the Trinity, but they don’t often look much different from the Unitarian churches down the road. To talk about God in a way that is uniquely Christian, our language must be filled with trinitarian language.

The filioque clause is not so heavenly minded that it is no earthly good. It is useful for Christians who must preach, sing, and think hard about God who is Three-in-One and has saved us and is keeping us until the Son of God, Jesus Christ, the second Person of the Trinity, comes again.