One of the main reasons that I’m Orthodox and not Roman Catholic is because of the Latin Church’s insertion of the Filioque into the Nicene Creed. In this article, I’m going to explain why I believe the theology behind this insertion is heretical, and why I therefore cannot in good conscience join the Roman Catholic Church. Please note that I’m open to changing my mind about this topic if someone can very persuasively demonstrate the arguments I present here to be invalid, but until such time, this is the view I hold, not because it’s convenient for polemics’ sake, but rather because, as will be shown in the section below on biblical theology, I think the Orthodox teaching on this matter leads to profound insights into our life in Christ. With that said, let’s begin.

Patristic Theology

In order to understand my opposition to the Filioque doctrine, it’s important to know what it even is in the first place. According to the Council of Florence, expressed in Pope Eugene IV’s papal bull Laetentur Caeli, it’s the belief that

The Holy Spirit proceeds from the Father together with the Son, eternally as from one principle […] the Son should be signified indeed as cause and principle of subsistence [existence] of the Holy Spirit, just like the Father… We declare that when holy doctors and fathers say that the holy Spirit proceeds from the Father through the Son, this bears the sense that thereby also the Son should be signified, according to the Greeks indeed as cause, and according to the Latins as principle of the subsistence of the holy Spirit, just like the Father. (Council of Florence, Session 6—6 July 1439, Definition)

The bull claims that the Son is the cause of the Holy Spirit, in the Greek sense of the term. Thus, the bull reasons, when the Greek Fathers write that the Spirit “proceeds through the Son,” what they mean by this is that the Son causes the Holy Spirit’s subsistence/existence, “just like the Father.” As we shall see, the reason why this is such a big issue, and why this was the issue over which the schism between East and West happened, is because such a belief is directly contradicted by the Greek Fathers themselves who wrote in detail about this topic.

[Throughout this section I will be referencing Edward Siecienski’s “The Filioque: History of a Doctrinal Controversy” quite a bit.]

St. Gregory the Theologian, one of the main figures at the Second Ecumenical Council, which authored the “and I believe in the Holy Spirit…” clause of the Nicene Creed, famously wrote that the causation of the Son and the Holy Spirit belongs only to the Father. To express this, after exhaustively explaining how the Father is the sole cause of the Son’s generation and the Spirit’s procession, he writes “everything the Father has, the Son has also, except causality” (Siecienski, pg. 42). From this we gather that, according to St. Gregory, the Father being the only “cause” of the Son and the Spirit is something irreducibly unique to Him alone, which means that the Son cannot be the cause of the Spirit as Florence teaches. Moreover, when considered in light of the fact that St. Gregory was one of the Fathers who participated in adding the phrase “who proceeds from the Father” to the Creed, it’s clear that this phrase was intended to convey the Greek understanding of the causality of the Spirit from the Father alone, just as speak of the Son being “begotten of the Father” was also intended to convey the Son being caused by the Father alone. Given it’s impossible to separate the theology of the Council Fathers from the theology of the Councils themselves, that the Filioque was interpolated into the very Creed St. Gregory helped propagate, isn’t a very good look for RC dogma.

The next Greek Father who has something to say about the Filioque is St. Cyril of Alexandria who, in his disputations with blessed Theodoret of Cyrus (Siecienski, pg. 48-50), was accused of believing that “the Spirit has his subsistence from the Son or through the Son” because of his usage of standard Alexandrian (and Latin) terminology that the Holy Spirit proceeds “and from the Son.” However, in his reply letter, St. Cyril made it clear that this is not what he believes, and that he recognizes, with blessed Theodoret, that the Father is the only one from whom the Spirit receives existence, confirming the statement that “the Holy Spirit does not receive existence from or through the Son, but proceeds from the Father and is called the proprium of the Son because of his consubstantiality.” Contrast St. Cyril’s denial of the Spirit receiving existence “from or through the Son” with Florence’s teaching that the Spirit does in fact receive existence “from the Son, just like the Father,” and that the Greek Fathers meant just this by the phrase “through the Son.” As is clear, this is not even close to what St. Cyril meant by this phrase, rather he’s clear that all this phrase implies is the consubstantiality of the Son and the Spirit.

What’s significant about this is that one of the main defenses of the Filioque in the Greek Fathers at the Council of Florence was the witness of Sts. Athanasius and Cyril, however given St. Cyril explicitly contradicts the teaching of Florence (and there’s a good chance that he understood 4th century Alexandrian theology better than medieval Latins did), it’s almost certain that St. Athanasius does as well, meaning that these two cannot be used as Greek support of the Filioque doctrine as understood at Florence, but rather serve as hard evidence against it.

Next we have St. Maximus the Confessor and his Letter to Marinus, which is perhaps one of the most important pieces of evidence in this whole debate, because it’s one of the earliest documented conflicts over the Filioque between East and West (unless you also count St. Cyril’s interaction with Theodoret). St. Maximus, who knew both Greek and Latin and was living in Rome, received word from his fellow Greeks that they were very concerned over the Latins’ usage of “Filioque,” fearing that it was the heretical belief that the aforementioned Sts. Gregory and Cyril had repudiated centuries earlier. First, this establishes that suspicion over the Filioque was not an after the fact justification for schism between East and West, but was an issue as early as the 7th century. Second, St. Maximus’ defense of the Latin Filioque is very important because he writes:

“They [the Orthodox Latins] showed that they themselves do not make the Son the cause of the Spirit for they know the Father is the one cause of the Son and the Spirit, the one by begetting and the other by procession, but they show the progression through Him and thus the unity of the essence.”

Once again remember Florence’s teaching that the Filioque means that the Son causes the Spirit’s existence, just as the Father does, and it specifically cites the Greek usage of this term. We see St. Maximus explicitly condemn this teaching, saying instead that the Orthodox position is that the Son is not “the cause of the Spirit,” but rather the one cause of the Son and the Spirit is the Father. Not only does St. Maximus explain what the Filiqoue does not mean, but he also explains what it does mean, by saying that the Spirit’s progression through the Son shows “the unity of essence,” or “consubstantiality.” Remember that this is exactly what St. Cyril said the phrase “through the Son” meant, and notice that it’s in direct contradiction to the Council of Florence, which claimed that the Greek Fathers meant by this phrase that the Son was a cause of the Spirit’s existence.

That this position contradicts the modern RC one is further evidenced by the fact that the Latins rejected St. Maximus’ Letter to Marinus as a basis for reunion at the Council of Florence, even though they were the ones to present it in the first place, not realizing that it contradicted their own position! (For an extensive treatment of this topic see Siecienski, ch. 4).

Lastly we have St. John of Damascus, who is in many respects seen as the spiritual successor to St. Maximus (and is my patron saint!) No Father of the Church taught against the modern RC Filioque as strongly as he did, explaining in detail that the Spirit is caused “by the Father alone” and that He proceeds “through the Son” by virtue of Their consubstantiality, which is precisely what the Greek Fathers before St. John had always taught:

And we speak likewise of the Holy Spirit as from the Father, and call Him the Spirit of the Father. And we do not speak of the Spirit as from the Son: but yet we call Him the Spirit of the Son. For if any one has not the Spirit of Christ, he is none of His Romans 8:9, says the divine apostle. And we confess that He is manifested and imparted to us through the Son […] All the terms, then, that are appropriate to the Father, as cause, source, begetter, are to be ascribed to the Father alone: while those that are appropriate to the caused, begotten Son, Word, immediate power, will, wisdom, are to be ascribed to the Son: and those that are appropriate to the caused, processional, manifesting, perfecting power, are to be ascribed to the Holy Spirit. The Father is the source and cause of the Son and the Holy Spirit: Father of the Son alone and producer of the Holy Spirit. The Son is Son, Word, Wisdom, Power, Image, Effulgence, Impress of the Father and derived from the Father. But the Holy Spirit is not the Son of the Father but the Spirit of the Father as proceeding from the Father. For there is no impulse without Spirit. And we speak also of the Spirit of the Son, not as though proceeding from Him, but as proceeding through Him from the Father. For the Father alone is cause. (An Exact Exposition of the Orthodox Faith, Book I, Chapter 8, 12)

In agreement with the Fathers before him, St. John teaches that the causation of the Son and the Spirit belongs to the Father alone, and that the Holy Spirit “does not proceed from the Son,” but rather proceeds “through Him,” which means that the Spirit is “manifested and imparted to us through the Son.” That this teaching contradicts Florence is as plain as day. For the Greek Father St. John Damascene, Florence’s sentiment that when the Greek Fathers used the phrase “through the Son” they really meant “from the Son” in terms of causation, is clearly false. What’s significant about this is that St. John was not just making this doctrine up, but rather firmly believed it to be the official position of the Greek Church (the “Exact Exposition of the Faith,” as his work was called) as did those Orthodox Christians after him.

With all that’s been written above, it should be very clear why the Greek East so strongly opposed the Latin interpolation of the Filioque into the Nicene Creed. However, what of the western Fathers? In the West, it is true that there are several Fathers who seem like they teach the Filioque, such as Sts. Augustine, Hilary, Leo, Gregory the Great, etc., however these Fathers never went into as great detail as the eastern Fathers, and thus they they weren’t as precise in defining the exact nature of the relationship between the Son and the Spirit (see Siecienski, ch. 3). What I mean by this is that, whereas Greek Fathers like Sts. Gregory, Cyril, Maximus, and John Damascene went into great detail explaining what exactly is meant by the phrase “the Spirit proceeds from/through the Son” (namely that it refers to consubstantiality and unity of essence, and not to causality being attributed to the Son), the Latin Fathers tended to simply use one of these phrases without actually explaining in great detail what they meant by it.

This isn’t to western Fathers’ discredit, it’s simply the case that the western Fathers were dealing with different questions than the eastern Fathers, and so they emphasized different things, most especially the Spirit’s consubstantiality with the Son, and they didn’t get caught up in the details of explaining the implications of the terminology used to describe this. It’s important to understand that terminology is not what’s at stake in the Filioque debate, rather it’s what is meant by this terminology that’s at stake. For example, someone could go around citing John 14:28, shouting “the Father is greater than the Son!” from the rooftops, and this terminology is perfectly valid given its use in Scripture. However, to determine whether or not this person is Orthodox, we would need them to explain in detail what exactly they think this terminology means. So it is with the Filioque. There’s no intrinsic issue with saying that “the Holy Spirit proceeds from the Father and the Son,” rather the issue can come about if you understand this phrase in the heterodox sense that Florence does, and not the Orthodox sense that the Greek Fathers so carefully articulated throughout the centuries.

More than this though, it was eastern Trinitarian theology that was accepted at the Ecumenical Councils of I Constantinople, all the way through II Nicaea, and so even if some western Fathers contradicted the eastern Fathers on this issue (which I don’t think they did, see Craig Truglia and Alura’s treatment of St. Augustine’s pneumatology here and here), there is no reason to exalt the western Fathers over the eastern Fathers, but if push comes to shove, there is very good reason to choose the latter as the lens through which we view the former on this specific topic, given everything that’s been explained above.

Biblical Theology

Now that I’ve fully articulated the patristic theology regarding the procession of the Holy Spirit, I’d like to move on to explaining why I believe the Orthodox teaching on this matter is the most coherent with Holy Scripture. To begin with, let’s take a genuine look at the classic polemical texts used in the debates about the Spirit’s procession:

“But when the Counselor comes, whom I shall send to you from the Father, even the Spirit of truth, who proceeds from the Father, he will bear witness to me; and you also are witnesses, because you have been with me from the beginning.” ‭‭(John‬ ‭15:26-27‬ )

Now, in this text, what we need to pay attention to is exactly how our Lord says the Spirit will come to the Apostles, and what He will do once among them. Christ says that He will send the Spirit from the Father. The significance of this language is that it explains what Christ means when He later says:

“But very truly I tell you, it is for your good that I am going away. Unless I go away, the Advocate will not come to you; but if I go, I will send him to you” (John 16:7).

Why is it that Christ cannot send the Spirit to the Apostles until He has ascended to His Father? This is a point that will be proved further as we explore the biblical texts, but the answer is this: Because in order for Christ to send the Spirit, He must ascend to heaven in His glorified Body and receive the Spirit from the Father as true God and true Man, in order that He might send it to His Apostles. This is something that is documented in the book of Revelation (which gives a heavens-eye view of Christ’s ascension):

“Then another angel took the censer and filled it with fire from the altar and threw it on the earth; and there were peals of thunder, voices, flashes of lightning, and an earthquake.” (Revelation 8:5)

In this passage, and indeed throughout Revelation, “another angel” is the incarnate Christ, and the fire that He takes from the altar of God and throws onto the earth is the Holy Spirit, a point made clear by the parallel language in Revelation 4:5, “From the throne issue flashes of lightning, and voices and peals of thunder, and before the throne burn seven torches of fire, which are the seven Spirits of God.

As stated above, this helps to clarify why the ascension of Christ was necessary in order for the Holy Spirit to be sent into the world, and why our Lord, in the initially cited verse from St. John’s Gospel, goes onto say that the Spirit of truth proceeds from the Father: Because it is from the Father’s altar that the Son “takes His censer and fills it” with the Holy Spirit, Who He then casts down upon the earth. In other words, the Son receives the Spirit from the Father, which enables Him to give the Spirit to His followers on earth.

Furthermore, in this same passage, our Lord goes onto say that the Spirit of truth, who proceeds from the Father, will bear witness to Him, just as the Apostles are to bear witness to Him because they have been with Him “from the beginning.” This is important to note because it implies that being a witness to the Son is related to being with Him “in the beginning,” thus establishing that the Holy Spirit, like the Apostles, has been with the Son since the beginning, thereby implying that everything that has been discussed above relates not only to the temporal manifestation of the Trinity in time, but also to the eternal manifestation of the intra-Trinitarian life.

With all of this in mind, let’s move on to some more classically polemical texts, and examine how they fit into the biblical picture we’ve constructed above:

Just as the Father has sent me, so I send you,” and when he had said this, he breathed on them, and said to them, “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained.” (‭‭John‬ ‭20:21-23‬)

Although there’s a lot to be said about this passage that specifically deals with the New Covenant priesthood and the sacraments (something I’ve explored before), what we want to know from this passage is more broad: Why exactly is it that the Apostles receive the Spirit from the Son, and what does this, generally speaking, enable them to do? Both of these questions are clarified in light of what St. John says about the Spirit earlier in His Gospel:

“And let the one who believes in me drink. As the scripture has said, ‘Out of the believer’s heart shall flow rivers of living water.” Now he said this about the Spirit, which believers in him were to receive; for as yet there was no Spirit, because Jesus was not yet glorified.” (‭‭John‬ ‭7:38-39‬)

In this passage, our Lord cites the Old Testament to reference what will happen to a true believer’s heart, namely that rivers of living water shall flow from it, something that St. John clarifies is a reference to the Holy Spirit. The logic here patterns what was said above: Just as Jesus receives the Spirit from the Father before sending Him to others, so too does a believer receive the Holy Spirit, which enables Him to flow out of said believer. This implies that the believer, like Christ, has the ability to enable someone else to receive the Holy Spirit. This is important to keep in mind when we look at an oft-cited prooftext for the Filioque:

“Then he showed me the river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb.” (Revelation 22:1)

Even RCs must admit that this passage is not talking about the hypostatic procession of the Holy Spirit, given the Greek word used to describe His “flowing” from the Father and the Son is “ἐκπορευόμενον,” which RCs are quick to point out is a term that can only be used to describe the Spirit’s hypostatic procession from the Father. So if that’s not what this passage is talking about, what is it saying?

I believe the answer is this: The Spirit flows from the Father and the Son’s thrones, which enables believers to partake of Him, for “him who desires shall take the water of life without price” (22:17). And once these believers receive the Spirit from the Father and the Son, so too shall the Spirit flow from them and water the whole earth with life. In other words, this passage is describing how the Spirit eternally dwells within and flows forth from the Father to the Son, and through Him, to us, and from us, to the whole world. St. Bede the Venerable came to a similar conclusion in his commentary on Revelation wherein he applies this passage to the Church “sowing the Spirit” in the world, in order to attain its fruits in the Age to Come. And, of course, this interpretation is further confirmed by the fact that, as shown above, Revelation is very clear that the Son must first receive the Spirit from the Father before giving Him to anyone else, and the Spirit is said to “flow” from the hearts of the faithful, just as He flows from Christ, meaning that our relationship to the Father and the Spirit is akin to the Son’s.

Once that’s understood, it makes perfect sense of why the Apostles, after receiving the Spirit from Christ, go onto give the Spirit to others throughout their ministry (Acts‬ ‭8:14-20‬). Moreover, this sheds enormous light on St. Paul’s teaching about our adoption as sons under the New Covenant:

But you are not in the flesh; you are in the Spirit, since the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him. But if Christ is in you, though the body is dead because of sin, the Spirit is life because of righteousness. If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ from the dead will give life to your mortal bodies also through his Spirit that dwells in you […] For all who are led by the Spirit of God are children of God. For you did not receive a spirit of slavery to fall back into fear, but you have received the Spirit of adoption. When we cry, “Abba! Father!” it is that very Spirit bearing witness with our spirit that we are children of God, and if children, then heirs, heirs of God and joint heirs with Christ—if, in fact, we suffer with him so that we may also be glorified with him. (‭‭Romans‬ ‭8:9-11, 14-17‬)

As I’ve explained before, if we want to understand what St. Paul is saying here, we have to understand the biblical theology of adoption. In the Bible, if you’re adopted into a family, then you are genealogically identical to those who were born into that family. This is the very reason why Jesus Himself receives the throne of His father David via His adoption by St. Joseph.

Thus, what St. Paul means by us receiving “the Spirit of adoption” is this: Because we have been adopted into the family of the Holy Trinity, we truly become “co-heirs with Christ” to the Father’s inheritance, and how this takes place is incredibly important: Through the Spirit. The Holy Spirit is referred to as “the Spirit of Christ” and “the Spirit of the Son” precisely because He is the Person by whom the Father is eternally united with the Son in love, hence why we too are incorporated into the love that the Father has for His Son through that same Spirit. Thus, because we have been adopted into this eternal family of Father, Son, and Holy Spirit, becoming co-heirs with the Son Himself, this means that we, by grace, have the same relation to the Father and the Spirit that the Son has by nature. Just as the Father loves the Son by giving Him the Spirit from all eternity, so also does the Father love us, His adopted sons, by giving us that same Spirit in our earthly lives; and just as the Son eternally reciprocates His love for the Father by the Spirit, so too do we reciprocate our love for God by the Spirit, as the priest says at every Liturgy: “The grace of our Lord Jesus Christ, the love of God the Father, and the communion of the Holy Spirit be with you all.”

I believe one of the most clear illustrations of this point is in the story of the Theophany, wherein we liturgically proclaim that “the Trinity was made manifest.” St. Luke tells us:

When all the people were being baptized, Jesus was baptized too. And as he was praying, heaven was opened and the Holy Spirit descended on him in bodily form like a dove. And a voice came from heaven: “You are my Son, whom I love; with you I am well pleased. (Luke 3:21-22)

We established above that the eternal relationship between the Son and the Spirit is one in which the the Father gives the Spirit to the Son, and this is the very act by which He loves the Son (just as the Father loves us by giving us this same Spirit, thus making us co-heirs with Christ). Here, we see a concrete manifestation of this eternal reality: The Father sends down His Holy Spirit upon Jesus, declaring that “You are my Son, whom I love.”

And just as the Son eternally reciprocates His love for the Father by the Holy Spirit, so too did He do this in time. St. Paul says that what it means to be a son of God “in the Spirit” is that the Holy Spirit dwells within you, and that all who are “led by the Spirit” are the children of God; this directly corresponds to how Christ is described in Luke‬ ‭4:1-18, where, after receiving the Spirit from the Father, He is both “full of the Holy Spirit,” i.e. the Spirit dwells within Him, and He “is led by the Spirit, in the power of the Spirit.” This is why St. Paul says the phrase that would go on to be debated for centuries: “Anyone who does not have the Spirit of Christ does not belong to him,” because, as has just been said, not only does the Spirit dwell within Christ, but it was by the Spirit that the Son was led during His earthly ministry, precisely because, just as the Father shows His love for the Son by sending Him the Spirit, so too does the Son reciprocate this love by the same Spirit, obediently following His Father’s command, even to the Cross. And it is this reciprocation of love by the Spirit that is the sense in which the Spirit is said to eternally “flow forth” or “proceed” from the Son, which is the eternal principle that enables Him to send us the Spirit in time, something that corresponds to how the Spirit temporally flows forth from us when we reciprocate our love for the Father by the Spirit, which I believe is the biblical basis for St. Seraphim of Sarov’s famous phrase, “acquire the Spirit of peace, and thousands around you will be saved.”

I’ll end this article with the words of St. Gregory Palamas (who’s venerated as a saint in the eastern rites of the RCC), who most clearly summed up the Orthodox teaching on the procession of the Holy Spirit:

[The] Spirit of the supreme Word is like an ineffable love of the Begetter towards the ineffably begotten Word himself. The beloved Word and Son of the Father also experiences this love towards the Begetter, but he does so inasmuch as he possesses this love as proceeding from the Father together with him and as resting connaturally in him. From the Word who held unity with us through the flesh we have learned also the name of the Spirit’s distinct mode of coming to be from the Father, and that the Spirit belongs not only to the Father but also to the Son. For he says, “The Spirit of Truth, who proceeds from the Father,” in order that we may recognize not a Word alone but also a Spirit from the Father, who is not begotten but who proceeds, but he belongs also to the Son who possesses him from the Father as Spirit of truth, wisdom and word. For truth and wisdom constitute a word appropriate to the Begetter, a Word which rejoices together with the Father who rejoices in him, according to what he said through Solomon, “I was the one [i.e., Wisdom] who rejoiced together with him.” He did not say “rejoiced” but “rejoiced together with,” for this pre-eternal joy of the Father and the Son is the Holy Spirit in that he is common to them by mutual intimacy. Therefore, he is sent to the worthy from both, but in his coming to be he belongs to the Father alone and thus he also proceeds from him alone in his manner of coming to be. (St. Gregory Palamas, The 150 Chapters)