Basil: Contra Eunomius Bk 3.5

Eunomius, who is audacious in every way, does not cower before the impending danger face by those who audaciously fired a blasphemous word against the Holy Spirit. He declares that the Spirit has no share in the divinity when he writes as follows:

He is third in rank and in nature, since he is brought into existence by the Father’s commandment and by the Son’s activity. He is honoured in third place, as the first and greatest of all, and the only thing of this kind made by the Only-Begotten, bereft of divinity and creative power.

He who says this seems not to believe that the divinity is in us, as John says about God: From this we know that he is in us, from the Spirit whom he has given us (1John 3.24). And the Apostle: Do you not know that you are a temple of God and that the Spirit of God dwells in you? (1Cor. 3.16) And again: In whom the whole structure is joined together and grows into a holy temple in the Lord, in whom you also are integrated into a habitation of God in the Spirit (Eph. 2.21-22). So, if God is said to dwell in us through the Spirit, how is it not blatantly impious to say that the Spirit himself has no share in the divinity? And if we call those who are perfect in virtue ‘gods’ and this perfection comes through the Spirit, how does he make other gods if he is himself bereft of divinity? Moreover, it is impious to say of the Spirit, as one can say of human beings, that the divinity honoured in him comes by participation and does not coexist with him by nature. For the one divinised by grace possesses  nature subject to change and falls away from the better state whenever he is careless.

This claim of Eunomius is clearly deposed to what has been handed down about the saving baptism: Go baptise in the name of the Father and of the Son and of the Holy Spirit (Matt. 28.19). Baptism is the seal of faith, and faith is an assent to divinity. for one must first believe, then be sealed with baptism. Our baptism accords with exactly what the Lord handed down: It is in the named of the Father, and of the Son, and of the Holy Spirit. In this formula, no creature or servant is ranked together with the Father and the Son, as if the divinity becomes complete in the Trinity. Everything external to them is a fellow-servant, even if generally some are valued more than others on account of their superior dignity.