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.