One of the great joys of my life has been the study of the classic treatise on the person of the Holy Spirit, written by Basil of Caesarea (c.330-379) and entitled simply On the Holy Spirit. In the early 370s Basil found himself locked in theological combat with professing Christians, who, though they confessed the full deity of Christ, denied that the Spirit was fully God. Leading these “fighters against the Spirit” (Pneumatomachi), as they came to be called, was one of his former friends, indeed the man who had been his mentor when he first became a Christian in 356, Eustathius of Sebaste (c.300-377). The controversy between Basil and Esuathatius, from one perspective a part of the larger Arian controversy, has become known as the Penumatomachian controversy.
Eustathius’ interest in the Spirit seems to have been focused on the Spirit’s work, not his person. For him, the Holy Spirit was primarily a divine gift within the Spirit-filled person, One who produced holiness [Wolf-Dieter Hauschild, “Eustathius von Sebaste”, Theologische Realenzyklopädie, 10 (1982), 548-549]. When, on one occasion at a synod in 364, he was pressed to say what he thought of the Spirit’s nature, he replied: “I neither chose to name the Holy Spirit God nor dare to call him a creature”! (Socrates, Church History 2.45).
For a number of years, Basil sought to win Eustathius over to the orthodox position. Finally, in the summer of 373 he met with him for an important two-day colloquy, in which, after much discussion and prayer, Eustathius finally acquiesced to an orthodox view of the Spirit’s nature. At a second meeting Eustathius signed a statement of faith in which it was stated that:
“[We] must anathematize those who call the Holy Spirit a creature, those who think so, and those who do not confess that he is holy by nature, as the Father and Son are holy by nature, but who regard him as alien to the divine and blessed nature. A proof of orthodox doctrine is the refusal to separate him from the Father and Son (for we must be baptized as we have received the words, and we must believe as we are baptized, and we must give honour as we have believed, to the Father, Son and Holy Spirit), and to withdraw from the communion of those who call the Spirit a creature since they are clearly blasphemers. It is agreed (this comment is necessary because of the slanderers) that we do not say that the Holy Spirit is either unbegotten for we know one unbegotten and one source of what exists, the Father of our Lord Jesus Christ, or begotten, for we have been taught by the tradition of the faith that there is one Only-Begotten. But since we have been taught that the Spirit of truth proceeds from the Father we confess that he is from God without being created. (Basil, Letter 125.3).
In Basil’s thinking, since the Spirit is holy without qualification, he cannot be a creature and must be indivisibly one with the divine nature. The confession of this unity is both the criterion of orthodoxy and the basis upon which communion can be terminated with those who affirm that the Spirit is a creature. This pneumatological position thus defines the precise limits beyond which Basil was not prepared to venture, even for a friend such as Eustathius.
Another meeting was arranged for the autumn of 373, at which Eustathius was to sign this declaration in the presence of a number of Christian leaders. But on the way home from his meeting with Basil, Eustathius was convinced by some of his friends that Basil was theologically in error. For the next two years Eustathius crisscrossed what is now modern Turkey denouncing Basil, and claiming that the bishop of Caeasrea was a Modalist, one who believed that there were absolutely no distinctions between the persons of the Godhead.
Basil was so stunned by what had transpired that he kept his peace for close to two years. As he wrote later in 376, he was “astounded at so unexpected and sudden a change” in Eustathius that he able to respond. As he went on to say: “For my heart was crushed, my tongue was paralyzed, my hand benumbed, and I experienced the suffering of an ignoble soul…and I almost fell into misanthropy… [So] I was not silent through disdain…but through dismay and perplexity and the inability to say anything proportionate to my grief.” (Letter 244.4)
Finally, he simply felt that he had to speak. His words were those of the one most important books of the entire patristic period, On the Holy Spirit.