On Angelic Holiness

St. Basil of Caesarea ca. 330-379

The powers of the heavens are not holy by nature; were it so there would in this respect be no difference between them and the Holy Spirit. It is in proportion to their relative excellence that they have their meed of holiness from the Spirit. The branding-iron is conceived of together with the fire; and yet the material and the fire are distinct. Thus too in the case of the heavenly powers; their substance is, perhaps, an aerial spirit, or an immaterial fire, as it is written, Who makes his angels spirits and his ministers a flame of fire; wherefore they exist in space and become visible, and appear in their proper bodily form to them that are worthy. But their sanctification, being external to their substance, superinduces their perfection through the communion of the Spirit. They keep their rank by their abiding in the good and true, and while they retain their freedom of will, never fall away from their patient attendance on Him who is truly good. (On the Holy Spirit 16.38)

Nothing is made holy except by the presence of the Spirit. The Word, the Artisan and Creator of the universe, gave to the angels their entry into existence; the Holy Spirit added their holiness to them. The angels were not created infants, to be gradually perfected by exercise until they became worthy of the reception of the Spirit; rather, in their initial formation and, as it were, mixed into the very substance of their being, they had holiness. (On the Psalms, 32:4)