In theology, Eastern Orthodoxy is the new black. These days it's harder and harder to find any serious Protestant commitment to the western confession of filioque. The denomination in which I'm teaching, for instance, omits the filioque from liturgical confessions of the Nicene Creed.
In recent Protestant theology, reluctance to confess the filioque seems to arise mainly from a general ecumenical sentiment on the one hand (as though such a confession would be impolite), and from an ill-informed and stereotyped criticism of Augustine on the other (as one finds everywhere in Colin Gunton's works, for example).
In one of my recent pneumatology classes, I tried to argue for the contemporary importance of the filioque. My argument was roughly as follows: In the preaching and worship of liberal Protestant churches, there is a good deal of emphasis on the autonomy of the Spirit. The Spirit is often invoked without reference to Christ, or to the biblical narrative, or to the events of salvation-history. We have hymns and prayers that celebrate "the Spirit" as a kind of generic Spirit of creation, a benevolent life-force that is universally active and available. The role of this Spirit, presumably, is to grant unmediated religious access to God – a kind of second saviour, an alternative to Christ. I once attended a particularly ghastly eucharist service, where the bread and wine were not once related to Christ, but simply to "the Spirit" who is at work in all the gifts of creation. Such a Spirit clearly could not be said to proceed "from the Son"!
It's precisely here that the filioque could function to safeguard the church's confession of the gospel. The role of the filioque is to tie the Spirit's work indissolubly to God's act in Christ; to confess that the action of the Spirit is part of the story of salvation-history, and not some independent avenue of God's presence in the world. A Spirit who proceeds simply "from the Father" can very easily be understood as a second way of salvation, operating remoto Christo and floating free of the events of salvation-history.
Karl Barth's defence of the filioque was partly motivated by this kind of concern. He wondered whether the Eastern church's refusal of the filioque is "a reflection of the very mystically oriented piety of the East, which, bypassing the revelation in the Son, would relate human beings directly to the original Revealer, the principium or fount of deity" (Göttingen Dogmatics, 1:129-30). (I look forward to learning much more about this when Ashgate releases David Guretzki's new book on Karl Barth and the Filioque – due out next month.)
This week I've also been immersed in Volumes 12 (Berlin, 1932-1933) and 13 (London, 1933-1935) of Bonhoeffer's Works. And I've been struck by the importance of the filioque in the struggle of the Confessing Church against the Deutsche Christen. The 1933 Bethel Confession (Bonhoeffer was one of its main writers) includes a section on the Holy Spirit which foregrounds the filioque:
"The church teaches that the Holy Spirit, true God for all eternity, is not created, not made, but proceeds from the Father and the Son.... We reject the false doctrine that the Holy Spirit can be recognized without Christ in the creation and its orders. For it is always as proceeding from the Son that the Holy Spirit judges this fallen world and establishes the new order, above all nations, of the church as the people of God. Only because the Holy Spirit proceeds from the Father and the Son does the church receive its mission to all nations" (Bonhoeffer, Berlin, 1932-1933, p. 399).
The notes from a 1933 pastors' conference records a discussion of this confession between Bonhoeffer and others:
In National Socialism, it is "first nature's grace, then Christ's grace. First creation, then redemption. This goes back to liberal theology. What is decisive is that the filioque is missing. The filioque means that the Spirit proceeds from the Father and the Son. The German Christians want to introduce a nature spirit, a folk [Volk] spirit, into the church, which is not judged by Christ but rather justifies itself." This is "German paganism" (Bonhoeffer, London, 1933-1935, p. 48).
As I've suggested before, liberal Protestant worship can easily degenerate into similar kinds of "paganism". A rediscovery of the theological significance of the filioque may be one way, in our time, of resisting this tendency and of preserving the christological shape of Christian confession of the Trinity.