Treatise Concerning the Trinity

Moreover, that When God is Called a Spirit, Brightness, and Light, God is Not Sufficiently Expressed by Those Appellations.

But when the Lord says that God is a Spirit, I think that Christ spoke thus of the Father, as wishing that something still more should be understood than merely that God is a Spirit. For although, in His Gospel, He is reasoning for the purpose of giving to men an increase of intelligence, nevertheless He Himself speaks to men concerning God, in such a way as they can as yet hear and receive; although, as we have said, He is now endeavouring to give to His hearers religious additions to their knowledge of God. For we find it to be written that God is called Love, and yet from this the substance of God is not declared to be Love; and that He is called Light, while in this is not the substance of God. But the whole that is thus said of God is as much as can be said, so that reasonably also, when He is called a Spirit, it is not all that He is which is so called; but so that, while men's mind by understanding makes progress even to the Spirit itself, being already changed in spirit, it may conjecture God to be something even greater through the Spirit. For that which is, according to what it is, can neither be declared by human discourse, nor received by human ears, nor gathered by human perceptions. For if “the things which God has prepared for them that love Him, neither eye has seen, nor ear has heard, nor the heart of man, nor even his mind has perceived;” what and how great is He Himself who promises these things, in understanding which both the mind and nature of man have failed! Finally, if you receive the Spirit as the substance of God, you will make God a creature. For every spirit is a creature. And therefore, then, God will be made. In which manner also, if, according to Moses, you should receive God to be fire, in saying that He is a creature, you will have declared what is ordained, you will not have taught who is its ordainer. But these things are rather used as figures than as being so in fact. For as, in the Old Testament, God is for this reason called Fire, that fear may be struck into the hearts of a sinful people, by suggesting to them a Judge; so in the New Testament He is announced as Spirit, that, as the Renewer and Creator of those who are dead in their sins, He may be attested by this goodness of mercy granted to those that believe.