How St. Athanasius Proved the Filioque
Despite the Latin West often being credited with developing the Catholic doctrine of the Filioque, I nonetheless believe that the best biblical argument in favor of this teaching was made by an Eastern Father, St. Athanasius the Great. This pillar of orthodox Trinitarian theology explicated his understanding of the Holy Spirit in his Letters to Serapion, which were written to combat a mutant form of Arianism that affirmed the full divinity of the Son, but denied the divinity of the Holy Spirit. This context is very important to keep in mind when reading the following argument from Athanasius:
As the Son is only-begotten offspring, so the Spirit, being given and sent from the Son, is himself one and not many, nor one from among many but only Spirit. As the Son, the living Word, is one, so must the vital activity and gift whereby he sanctifies and enlightens [the Spirit] be one perfect and complete; which is said to proceed from the Father because it is from the Word, who is confessed to be from the Father, and shines forth and is sent and is given. The Son is sent from the Father, for he says, “God so loved the world that he gave his only begotten Son.” The Son sends the Spirit; “If I go away,” he says, “I will send the Paraclete.” The Son glorifies the Father, saying, “Father, I have glorified thee.” The Spirit glorifies the Son, for he says, “he shall glorify me.” The Son says, “the things I have heard from the Father speak I unto the world.” The Spirit takes of the Son; “he shall take of mine,” he says, “and declare it unto you.” The Son came in the name of the Father. “The Holy Spirit,” says the Son, “whom the Father will send in my name.” But if in regard to order and nature the Spirit bears the same relation to the Son as the Son to the Father, will not he who holds the Spirit to be a creature necessarily hold the same to be true also of the Son?
St. Athanasius, First Letter to Serapion, PG, 26:576D-80B, qtd. in Fr. Thomas Crean, Vindicating the Filioque, p. 47.
St. Athanasius’ argument for the consubstantiality of the Son and the Spirit is absolutely brilliant. Remember that both Athanasius and his heretical interlocutors agreed on the consubstantiality of the Father and the Son, this was their common ground. What the Alexandrian bishop is trying to do here is take that shared assumption and demonstrate that, if you deny the full divinity of the Spirit, you end up denying the full divinity of the Son as well.
In order to do this, he starts by teaching that just “as the Son is [the] only-begotten offspring [of the Father], so the Spirit” is “sent from the Son.” Right off the bat we see a conflation of the eternal and temporal Trinitarian relations. The Son being eternally born of the Father is, for Athanasius, comparable to the Holy Spirit being “sent from the Son.” This is reminiscent of St. Augustine’s teaching that the temporal missions of the divine persons reveal their eternal relations, and the Saint goes even further in the next sentence. Commenting on why the Holy Spirit is said to “proceed from the Father” (Jn 15:16), he says that the Spirit “is from the Word, who is confessed to be from the Father.” In other words, according to St. Athanasius, the Spirit’s relation to the Father is mediated by the Son, and this is made known to us through their temporal missions. From here, Athanasius goes on to observe the striking parallels between the Father-Son and the Son-Spirit relationships in the Gospel of John, which he uses to prove that, if the Son is divine, the Spirit must be as well.
According to the Apostle John, St. Athanasius notes, the Son is sent by the Father (Jn 3:16); the Son glorifies the Father (Jn 12:28); the Son hears from the Father and declares what He hears (Jn 8:26); and the Son came in the name of the Father (Jn 5:43). St. Athanasius assumes that both himself and the heretics agree that these passages affirm the full divinity of the Father and the Son. They demonstrate that the Son receives the divine essence from the Father, nobody disputes this. However, this is where the Saint shows the heretics’ inconsistency. According to the very same Apostle, the Spirit is sent by the Son (Jn 15:26); the Spirit glorifies the Son (Jn 16:14); the Spirit hears from the Son and declares what He hears (Jn 16:14-15); and the Spirit comes in the name of the Son (Jn 14:26). From this Athanasius reasons that “in regard to order and nature the Spirit bears the same relation to the Son as the Son to the Father.” In other words, because Scripture describes the Son-Spirit dynamic in the same terms as the Father-Son dynamic, if the Son receives the divine essence from the Father then the Spirit must receive the divine essence from the Son. This is why the Doctor asks, “will not he who holds the Spirit to be a creature necessarily hold the same to be true also of the Son?”
St. Athanasius’ fundamental point is that, if the Spirit receives His essence from the Son just as the Son receives His essence from the Father, would not the Spirit being a creature require the Son to be a creature also? After all, if the Spirit receives a created nature from the Son, then this would indicate that the Son Himself has a created nature. However, since both Athanasius and his interlocutors rejected Arianism, this logic is an air-tight demonstration of the Holy Spirit’s full divinity. The Spirit receives the divine essence from the Son just as the Son receives the divine essence from the Father, thereby showing all three persons to be consubstantial. Athanasius’ argument is thus also a biblical proof for the Filioque, since the Saint uses Scripture to show that the Son is the origin of the Holy Spirit’s divinity, i.e. a principle of the Spirit’s hypostasis. In my opinion, this argument is so forceful it can stand on its own terms, even apart from the authority of St. Athanasius.
In conclusion, one can see that the pre-schism East and West were not actually of different minds on the question of the Spirit’s procession. Although they articulated the Filioque in different languages and contexts, the Greek and Latin Fathers were in full agreement that the Spirit receives His hypostatic origin from the Son. This is why I do not think it is unlikely that St. Athanasius may have had something to do with the Athanasian Creed after all, since that text boldly asserts the doctrine of the Spirit’s procession from the Son that this Alexandrian Saint articulated. Regardless, though, the point remains that Athanasius was a Catholic Filioquist.
I disagree with your read here, but regardless, no individual has authority over the Ecumenical Council, and the filoque remains an innovation imposed, not received, and is therefore a heresy denounced in unequivocal terms by many holy fathers including several popes.
It must be noted that what Saint Athanasius speaks of here is not about the doctrine of the filioque as pronounced by the Council of Florence, which says, “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”. This is not the case because note how Saint Athanasius says “the Spirit bears the same relation to the Son” and not both the Father and the Son, thus the relation here is one of sending. If it were the Filioque, it would say the same relation to the Father and the Son.
Saint Athanasius also rebukes any spiritive relation of the Son to the Holy Spirit in his homily, as he affirms only one head and source of Divinity in his words; “Thus in the Holy Trinity, there is one divinity and one faith”:
“But this is not how things are for the divinity. For God is not like a human being [Numbers 23:19]. Nor does he have a nature that is divisible into parts. Hence, he does not beget the Son by being divided into parts, so that the Son may also become the father of another, for he is not from a father. Nor is the Son a part of the Father. Hence, he does not beget as he has himself been begotten, but is whole from whole, Image [Colossians 1:15; 2 Corinthians 4:4] and Radiance [Hebrews 1:3]. 1.16.6. In divinity, the Father is a father in the proper sense and the Son a son in the proper sense. In their case, the Father's name has always been "Father" and the Son's name "Son? And just as the Father could never have been a son, so too the Son could never become a father. And just as the Father will never cease to be only a father, so too the Son will never cease to be only a son. 1.16.7. Therefore, it would be sheer insanity to imagine a brother for the Son and to apply the name "grandfather" to the Father. In the Scriptures, the Spirit is never called a son, lest he be considered a brother. Nor is he called a son of the Son, lest the Father be thought of as a grandfather. Instead, the Son is called the Son of the Father, and the Spirit is called the Spirit of the Father, and thus in the Holy Trinity, there is one divinity and one faith.
Saint Athanasius' Epistle to Serapion 1 section 1.16.5-16.7”