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Historical origins
As Johannes Grohe has pointed out, a regional council in Persia in 4l0 introduced one of the earliest forms of the filioque in the Creed; the council specified that the Spirit proceeds from the Father “and from the Son.” Coming from the rich theology of early East Syrian Christianity, this expression in this context is authentically Eastern. Therefore, the fulioque cannot be attacked as a solely Western innovation, nor as something created by the Pope.
In the West, St. Augustine of Hippo taught that the Spirit came from the Father and the Son, though subordinate to neither. His theology was dominant in the West until the Middle Ages, including his theology of the Trinity. Other Latin Fathers also spoke of the Spirit proceeding from both the Father and the Son. While familiar in the West, this way of speaking was virtually unknown in the Greek speaking, Eastern Roman Empire.
Here for example, is St. Augustine’s teaching that the Spirit proceeds from the Father and the Son:
But when the Father is known by someone in time he is not said to have been sent. For he has not got anyone else to be from or to proceed from. Wisdom says, I went forth from the mouth of the Most High (Sir 24:5), and of the Holy Spirit he says, He proceeds from the Father (Jn 15:26), but the Father is from no one.
Just as the Father, then, begot and the Son was begotten, so the Father sent and the Son was sent. But just as the begetter and the begotten are one, so are the sender and the sent, because the Father and the Son are one, so too the Holy Spirit is one with them, because these three ate one (1 Jn 5:7). And just as being born means for the Son his being from the Father, so his being sent means his being known to proceed from him… Nor, by the way, can we say that the Holy Spirit does not proceed form the Son as well; it is not without point that the same Spirit is called the Spirit of the Father and of the Son. And I cannot see what else he intended to signify when he breathed and said Receive the Holy Spirit (Jn 20:22). Not that the physical breath that came from his body and was physically felt was the substance of the Holy Spirit proceed from the Son as well as form the Father. Surely you would have to be out of you mind to say that it was on Spirit which he gave by breathing and another which he sent after his ascension. No, the Spirit of God is one, the Spirit of the Father and of the Son, the Holy Spirit who works all ways in all men (1 Cor 12:6). . .
By saying then, Whom I will send you from the Father (Jn 15:26), the Lord showed that the Spirit is both the Father’s and the Son’s. Elsewhere too, when he said, whom the Father will send, he added, in my name (Jn 14:26). He did hot however say, “whom the Father will send form me” as he had said whom I will send from the Father (Jn 15:26), and thereby he indicated that the source of all godhead, or if you prefer it, of all deity, is the Father. So the Spirit who proceeds from the Father and the Son is traced back, on both counts, to him of whom the Son is born.2
In the Latin-speaking Church, the phrase and and the Son (in Latin filioque) was first added to the Nicene Creed at the Synod of Toledo in Spain in 447. The formula was used in a letter from Pope Leo I to the members of that synod, responding to heresies they were confronting. (Primarily, it was added to the Creed in order to oppose the Arian heresy, which taught that the Son was a creature and not God. This heresy began with Arius, a priest of Alexandria.) At the third synod of Toledo in 589, the ruling Visigoths, who had been Arian Christians, submitted to the Catholic Church. They were obliged to accept the Nicene Creed with the filioque.
(In the East, Arianism was opposed, not with the filioque but rather with an orientation of many of the prayers of the Divine Liturgy to “Christ Our God. This development in the East, with a comparable, dogmatic concern, occurred much earlier, in the fourth century, when Arianism in the East was widespread and greatly controverted.)
