The Latin filioque is derived from two words. Filioque = que (and) filio (son). Thus, the filioque refers to the phrase, “and the Son.” Augustine is the Father of the filioque, the distinctively western interpretation of the procession of the Spirit. The Council of Constantinople (381) affirmed simply that the Spirit proceeds from the Father. Emphasizing the unity of God, Augustine affirmed that the Spirit proceeded from both the Father and the Son (filioque). This was, according to Augustine, because the Father has “given to the Son that the same Spirit should proceed from Him.” This teaching tended to emphasize the unqualified deity of the Son.
During the Medieval period when the Eastern and Western halves of the Church were drawing apart, the most important bone of contention as to doctrine was the controversy over the filioque. In 589 at the Synod of Toledo (in the west) the word, filioque, was added to the Nicene Creed. It would now be read in the West that “the Spirit proceeds from the Father and the Son.” This addition to the creed was offensive to many in the East.
Actually, in my opinion the difference between the East and West on this issue has been vastly inflated both then and now. Filioque was more an excuse to divide than a real reason to divide. Why do I affirm that the difference between East and West on this issue has been wrongly inflated? I say this because Augustine and premier Eastern theologians like John of Damascus (d. after 750) actually approached very closely to each other’s position on this issue.
As we have seen, Augustine did not teach that the Spirit from the Father and Son equally. What he actually said was that the Father has “given to the Son that the same Spirit should proceed from Him.” In this formula primacy and monarchy of the Father in the procession of the Spirit is maintained.
Quite similarly, John of Damascus in his definitive presentation of the Eastern doctrine of the Trinity taught that the Spirit proceeds from the Father through the Son. Though he rigidly rejected all subordinationism, he thought of the Father as the source of the Godhead. Yet one could say on the basis of his formula that the Spirit proceeds from both the Father and the Son.
Of course, the Western and Eastern views have been and may be understood in quite contrary ways. The Western view may be presented as presenting two ultimate sources for the procession of the Holy Spirit. The Eastern view may be presented as if the Spirit proceeds from the Father in a direction quite divorced from the person and work of the Son. Each of these extremes tends to heresy and, in fact, have been used in the interests of heresy. The extreme Western view denies the primacy of the Father in the Trinity and moves in the direction of Egaliarianism and Modalism. The extreme Eastern view seems to divorce the Son and Spirit and has been used (by Inclusivists like Clark Pinnock) to teach that the Spirit may be active where the Son is not known.
The best theologians of both East and West (Augustine and John of Damascus) have actually interpreted this issue in a way that has moved in the direction of rapprochement. They have understood the procession of the Holy Spirit, in spite of the filioque, in ways that are quite similar. I do not believe that this issue needs to be as divisive as it has become, just so long as the extreme views on either side are avoided.