The Filioque: What it is and Why it Matters

The Trinity is everything. It’s the defining doctrine of Christianity which ties all others together.  The Trinity is not an inconsequential abstract thought. It is the nature of the One True God. We’re privileged to have the opportunity to study who God is and what He has revealed to us in His Word.  However, when discussing the deep things of God we must be careful as to avoid error, falsehoods, and downright heresies. The nature of the generation and procession of the persons of the Trinity is an area of great intrigue and when studied sharpens the minds of believers.  The Filioque is one such area. But what is the Filioque, and why does it matter?


The base translation of the Latin “filioque” is “and the son”. At its core, the Filioque Clause is the teaching that the Holy Spirit eternally proceeds from both the Father and the Son. While this is an accurate summary of the doctrine it is too basic and needs context regarding the nature of the Father and the Son. To formulate a functional definition, that can be accepted regardless of one’s position on the Filioque, two qualifiers must be set forth.


First, for the Father to be Father He must generate the Son. This sounds like a given, but when ancient Arians claimed that God is the Father and Christ is the Son there must be further explanation of the Father and Son dynamic. The generation of the Son must be eternal for God the Father to always be the Father (John 17:1-5). There cannot be a time when the Son was not else there would have been a time when the Father was not Father. If the personal attribute of Fatherhood was at one point gained by a temporal generation of an offspring, God is mutable, and part of His being is dependent on His creation (i.e. the Son) (1). The claim made by Christ that He and the Father have always been one (John 10:30) was enough to warrant His death in the eyes of the Jews because this claim made Him equal with the Father (John 10:31-33). Therefore, there is a Scriptural precedent within God of the causality of persons while maintaining equality in essence.


Second, for the Holy Spirit to be the Holy Spirit and not another “Son” His procession must be ontologically different from the Father’s generation of the Son (2). The Son eternally generating from the Father is what makes Him the Son. If the Spirit was of that same generation then He would be another type of Son. The Spirit being sent from the Son as well as the Father in time (John 15:26) would lead to a Trinitarian discontinuity if this procession didn’t exist ontologically (within the divine nature) as well as economically (how the Trinity interacts with each other). It’s important to note here that the unique nature of the procession of the Holy Spirit isn’t about His essence. His proceeding from both Father and Son doesn’t make Him an unequal or disunified person within the Trinity, but rather, in the words of Charles Hodge, “…this procession concerns the personality and operations of the Spirit, and not His essence” (3).


With these qualifiers in mind, the working definition of the Filioque Clause that will be examined in this article is as follows: Within the Trinity, the Father being Father eternally generates the Son who eternally proceeds from the Father as Son. The Father and the Son eternally engage in the procession of the Holy Spirit who eternally proceeds from the Father and the Son as the Holy Spirit. This explanation of the Filioque may be helpful, but why does this doctrine matter?


The Great Schism of 1054 is the accepted date of the official split of the Eastern and Western churches. It took a thousand years for the split in the church to take place, and there are varied reasons for it, but in the middle of this division is the Filioque. The history of the Filioque is one that is often marked by times of miscommunication, misinformation, and misinterpretation. For the sake of space, consideration of the historical trajectory of the Filioque will begin with the letter of Maximus the Confessor to Marinus in the 7th century and then a few key events and people will be examined as well as a modern look at how East and West engage the doctrine.


Maximus the Confessor, an Eastern father, wrote a letter to Marinus assuming that the recipients embraced the orthodox understanding of the Trinity and therefore his goal was not to write a polemic regarding the Trinity in the fashion of Basil or Augustine, but rather to encourage the Christian to understand their union to Christ and how they “…participate in the divine life revealed in the person of the Word made flesh” (4). The letter by Maximus has been quoted by both East and West to confirm or deny the legitimacy of the Filioque. However, when one reads the letter it is ambiguous in detail and doesn’t lay out a systematic look at the doctrine, but, according to Siecienski, when the letter is read in light of Maximus’ understanding of the nature of the Father-Son relationship it could be argued that the letter butts heads with both the modern Eastern and Western view (5).


Following the Letter to Marinus, the East didn’t engage in writing about the doctrine, and the west continued in holding to it as orthodoxy (6). There were varied skirmishes in the 8th century about the Filioque but things heated up when Photius got involved. Photius, the Patriarch of Constantinople from 858 – 867, and again from 877-886, took issue with the teachings regarding the Filioque and responded in writing out the following arguments against the Filioque. He wrote that if there were two sources of the Spirit that the Trinity is transformed into a dual divinity; that the procession of the Spirit from the Son is not necessary because of the perfect nature of the Father; that the Son encroaches on the operation of the Father and becomes a form of semi-Sabellianism (The heresy which taught that the Father, Son, and Holy Spirit are three different modes of a singular god) if involved in the procession of the Spirit; and that the procession of the Spirit from the Son would make him a type of father to the Spirit (7). Photius would be a major point of contention within the church and during his life was elected bishop and deposed multiple times. He denounced the teachings of the Pope regarding the Filioque and died in exile in 895.


On the Western side of the “Photian Schism” Pope Nicholas of Rome sent out a call for theologians to refute the arguments against the Filioque made by Photius. One of the important elements in this call would be that two men, Anastasius Bibliothecarius and John Scotus Erigena, used Maximus the Confessor to “prove” that the Filioque was the tradition of the Church. Anastasius’ most important contribution was that he “Not only did he reintroduce the witness and theology of Maximus the Confessor but he also repeated Maximus’s explicit denial that the Son is a cause or principle of the Spirit” (8). This gave the Latin church an orthodox jumping-off point for further development of the Filioque, and freedom to add to the economic work of the Son.


The Photian Schism was proceeded by the Great Schism and subsequent attempts at reuniting the Eastern and Western churches. These would all fall short of reconciliation and lead to the Council of Ferrara-Florence in 1438-39. Here Mark of Ephesus, a monk theologian from Constantinople, would play a key role in leading the Greek delegates in the debate with the Latins, whom he accused of using partial and misinterpreted Patristic texts (9).


It can be seen in the debate between Mark and the Western theologians that the East and West had grown so far apart that they were effectively shooting past each other’s arguments in ignorance of cultural, historical, and ecclesiastical differences. The debates were devolving into uncharitable comments and at points even obstinate refusal to hear out the opposing speaker (10). It became clear that the East would never unconditionally accept the Filioque clause, even so, after the council all the delegates, apart from Mark who considered the Latin church as engaging in heresy, signed an agreement affirming the Filioque, and reunification of the two churches.


The excitement was short-lived. When the Greeks returned home, they found that the local church leaders in the East weren’t interested in compromising with the West and a large majority of Eastern churches rejected the decision reached at the Ferrara-Florence council. The compromise at the council with the West caused also caused international relational problems between the Russian and Greek leaders (11). Constantinople would fall shortly after to the Ottomans in 1453, and the division continued and is still the reality between the East and West.


The Roman Catholic Church holds to the ruling of Ferrara-Florence and currently teaches the following about the Filioque:

“The Latin tradition of the Creed confesses that the Spirit “proceeds from the Father and the Son (filioque)”. The Council of Florence in 1438 explains: “The Holy Spirit is eternally from Father and Son; He has his nature and subsistence at once (simul) from the Father and the Son. He proceeds eternally from both as from one principle and through one spiration… And, since the Father has through generation given to the only-begotten Son everything that belongs to the Father, except being Father, the Son has also eternally from the Father, from whom he is eternally born, that the Holy Spirit proceeds from the Son.”

 Roman Catholic Catechism 246

The Eastern Church continues to teach elements of the arguments of Photius and holds that the West inserted the Filioque illegitimately into the Nicene Creed. The Eastern Church rejects the terminology of “Filioque” and insists that the Spirit is only economically sent from the Son and doesn’t proceed from Him eternally, that is the work of the Father (12). But even with these theological differences the Orthodox Church and Roman Catholicism have, and continue, to engage in dialogue regarding the unification of the two churches.


As seen above, this simple statement has lead to massive division in church history. But to fully see why this doctrine matters, and what’s at stake, we’re going to look at Athanasius’ letter to Serapionem. An important thing to note is that in this letter Athanasius wasn’t on the nature of the procession but rather the fact that the Holy Spirit was an equal member of the Godhead (13). This isn’t to say that the Filioque isn’t evident in this letter, but rather that it is underlying the logical consistency of Athanasius’ argument and the doctrine of the Trinity in general. When the text is examined it will show that the Spirit’s uniqueness of persona is directly related to His procession of the Son. Athanasius highlights the consubstantial nature of the Spirit and his direct influence in salvation and how the Spirit is only able to engage in our salvation because of His divinity.

“If this is your attitude, what hope have you? Who will unite you to God, if you have not the Spirit of God, but the spirit which belongs to creation? How rash and careless on your part to reduce the Father and his Word to the level of creatures, and yet to set the creatures on a level with God! For that is what you are doing when you imagine the Spirit as a creature and rank him with the Triad. What madness too on your part to impute injustice to God, in that not all angels nor all creatures, but one from among them, is numbered with God and his Word!”

 Athanasius, Epistula Ad Serapionem 1.26

Playing a role in salvation automatically numbers the Spirit as an equal member of the Godhead. But again, the issue of uniqueness must be brought up. How could the Spirit be numbered among “God and his Word” if is procession is the same as the Word? This is where the historical argument by Photius and the Eastern Church is seen to be lacking in substance. His argument that if there are two sources of the Spirit that the Trinity is a duality runs into an issue when it is worked backward into his own view of the Trinity. If there is but one source for the procession of the Spirit, then there is an order of causality that would make the Spirit lower than the Son when considering his work in the salvific economy. The Spirit would be reacting to the work of the Son while not ontologically proceeding from the Son, therefore, disunifying the essence of the Trinity.


How could the Son send the Spirit with the Father (John 15:26) if the Spirit isn’t already proceeding from the Son? Did the Son gain “authority” over the Spirit following the ascension that wasn’t there before the incarnation? No, He was able to send the Spirit because the Spirit was already proceeding from the Father and the Son and when the work of the Son was accomplished, He was sent in order to unite us to God. As Athanasius put it how could we be united to God if he is a creature? But further, how could we be united to God if the operation of the Spirit was altered through the work of the Son in redemptive history?


So, why does the Filioque matter?  The answer is simply that it matters because the ontological nature of the Trinity determines how God accomplished our salvation. The Spirit must proceed from both the Father and Son to make the economic Trinity consistent.



1- Bavinck, Herman. Reformed Dogmatics. Vol. 2. Grand Rapids, MI: Baker Academic, 2004. 272-273

2- Frame, John M. Systematic Theology: An Introduction to Christian Belief. Phillipsburg, NJ: P & R Publishing, 2013. 496

3- Hodge, Charles. Systematic Theology. Vol. 1. Peabody, Massachusetts: Hendrickson Publishers, 2003. 477

4- Siecienski, A Edward. “The Authenticity of Maximus the Confessor’s Letter to Marinus: The Argument from Theological Consistency.” Vigiliae Christianae 61, no. 2 (2007): 189–227

5- Siecienski, A. Edward. The Filioque: History of a Doctrinal Controversy. 85

6- Ibid 87

7- Ibid 101

8- Ibid 108

9- Kappes, Christiaan. “A Latin Defense of Mark of Ephesus at the Council of Ferrara-Florence (1438-39).” Greek Orthodox Theological Review 59, no. 1–4 (Spring-Winter 2014): 161–230

10- Ibid 171-173

11- Ferguson, Thomas. “The Council of Ferrara-Florence and Its Continued Historical Significance.” St Vladimir’s Theological Quarterly 43, no. 1 (1999): 71-72

12- North American Orthodox-Catholic Theological Consultation. 2004. “The Filioque: A Church Dividing Issue?” The Greek Orthodox Theological Review 49 (3–4): 384-85

13- Jones, Ian. “The Procession of the Holy Spirit: Exploring Points of Contact and Divergence between Augustinian and Eastern Trinitarian Theologies.” St Vladimir’s Theological Quarterly 61, no. 3 (2017): 275

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