Belief in the Trinity makes Christianity stand out. This is true for a number of reasons, including the importance that this doctrine places on faith (how else can you explain how one is three and three are one?), trust in the Christians of the past (most contemporary Christians do not excavate the Trinitarian and Christological controversies of the early Church for themselves), and for the importance of relationship in the Christian tradition (the Trinity affirms the necessity of love and companionship, especially among those created in the image of God). Yet the exceptionality of this belief also makes it fraught with potential misunderstandings, misapplications, and outright heretical appropriations.
Such was the context of Agobard of Lyon (c. 779-840 CE), who was (among other things) engaged in Trinitarian-based controversies concerning Adoptionism and the procession of the Holy Spirit. In Agobardi sermo (more commonly called “On the Truth of the Faith and the Establishment of All Good”), Agobard outlines true Christian faith and exhorts his audience toward love of eternal things and good works. This article briefly considers how Agobard understood the person and work of the Holy Spirit as indicated in this sermon.
Agobard follows an orthodox Trinitarian formulation of the Godhead, writing that Christian faith consists of belief in “one almighty God, Father, Son, and Holy Spirit, true Trinity, true Unity.” He goes on to substantiate the formula with a series of orthodox descriptions of the nature and relationship of the three persons. After talking about the Godhead and Father, he then dwells upon the person and work of the Son for an extended period, focusing especially on Christ’s equality with the Father and unique role as the God-Man who was born of the Virgin Mary and suffered death for the sake of humanity’s redemption.
As was suggested by Joshua Schendel of Saint Louis University, this part of Agobard’s sermon appears to follow the outline of the Nicene Creed: a confession of Father, Son, and (as we will see below) Spirit. While affirming a basic Trinitarian outline, Agobard writes about the Father (though not too much, for He remains transcendent and the basic presupposition of monotheism) and then dwells lengthily upon the Son, much as the Creed and Councils had done. When it comes to the Holy Spirit’s portion of the sermon, however, Agobard provides us with precious little which explicitly concerns who he thinks the Holy Spirit is and what the that member of the Godhead does.
Agobard does offer an affirmation of the filioque clause of the Nicene Creed, that the Holy Spirit “proceeds from the Father and the Son.” And his explanations of the Trinity confirm the Holy Spirit’s divinity, eternity, equality with Father and Son, transcendence, and wisdom. However, when it comes to discussing the person of the Holy Spirit, He gets short shrift, for Agobard moves from a discussion of the Son into a discussion of the forces of evil against which the Church must contend. While brief treatment of the Holy Spirit in Christian theological treatises was not new to Agobard, it nonetheless remains problematic for a robust Trinitarian theology. That is, presupposing the Father, spending copious amounts of time on the Son, and then offering a tacit affirmation of the Holy Spirit sounds like an excellent way to end up with a functionally binitarian Godhead and a weak pneumatology. This in mind, the Eastern critique of the filioque as denigrating and subordinating the Holy Spirit sounds rather accurate.
Yet, to see the “page time” that a discussion of the Holy Spirit gets in Agobard as a direct indication of his doctrine of the Holy Spirit is ultimately problematic, for it presumes that the person of the Holy Spirit is the focus of pneumatology and not His works. For Agobard, at least, the Holy Spirit exists not as an abstract, amorphous transcendental, but rather as the “empowerer” of the work of the Church. That is, the Holy Spirit should not be approached through philosophical musings but through the works o the Church on earth. Much like the Creed, then, which discusses the Holy Spirit in relation to the speaking of the prophets, work of the Church, baptism, forgiveness of sins, and coming resurrection, Agobard teaches the truth of the Holy Spirit through the Church’s struggle against the devil and enemies of faith, struggle towards good works, resistance of the Anti-Christ, desire to live out the grace of baptism, adherence to the path of Christian love, and persistence in prayer.
For Agobard, then, his pneumatology and ecclesiology are intricately connected, for the Holy Spirit works through the Church and the People of God. To mix some metaphors, the pouring out of the Spirit comes through and to the Body of Christ. We may thus call Agobard’s view of the Holy Spirit something like “efficacious procession”, for the Holy Spirit proceeds not only from the Father and the Son, but also into the life and workings of those who serve the Holy Trinity. In this view, a vitalized pneumatology consists of Christians loving and serving God, neighbor, and world through resistance to evil, works of service, prayer, and the sacraments. This seems a pneumatology worthy of consideration even in today’s theological context, enabling Christian practice to be understood as inherently God-like and valuable. Thus, we may too be able to learn from Agobard on how the efficacious procession of the Holy Spirit becomes the efficacious works of the Church.
 On the human implications of relationship in the Imago Dei, see the Conciliar Post Round Table on the Image of God (13 November 2014).  Agobard of Lyons. “On the Truth of the Faith and the Establishment of All Good.” Early Medieval Theology. Edited and translated by George E. McCracken and Allen Cabaniss. Louisville: Westminster John Know Press, 1957. 334-362.  Ibid., 335, section III.  Ibid., 336-337 section III.  Ibid., 337-339, sections IV-VI.  Ibid., 339-345, sections VII-XI.  Joshua Schendel. “Agobard and Eriugena.” Saint Louis University. Presentation. 19 February 2015.  Nicene Creed.  Agobard, 336, section III.  This is most evident in the original Nicene Creed of 325, which ended simply with the words καὶ εἰς τὸ Πνεῦμα τὸ Ἅγιον (“and in the Holy Ghost”).  Whether this is the legacy of the Western Christian Church or not, is the topic of another article.  For some examples, see the linked sources here.  Niceno-Constantinopolitan Creed (381 CE): “And in the Holy Spirit, the Lord and life-giver, Who proceeds from the Father, Who with the Father and the Son is together worshipped and together glorified, Who spoke through the prophets; in one holy Catholic and apostolic Church. We confess one baptism to the remission of sins; we look forward to the resurrection of the dead and the life of the world to come. Amen.”  Agobard, 345-347, section XII.  Ibid., 347, section XIII.  Ibid., 348-355, sections XIV-XVIII.  Ibid., 355-6, section XIX.  Ibid., 356-358, sections XX-XXII.  Ibid., 359-362, sections XXIV-XXVIII. This post originally appeared here.