From THE FUNDAMENTAL GRAMMAR OF AUGUSTINE’S TRINITARIAN THEOLOGY by Lewis Ayres

In Book 7 of the Confessions, Augustine sets out for us what was perhaps the most important shift in his understanding of God, a shift to a position that basically remained with him until his death.10 He tells us that he had originally conceived of God as an extended, and perhaps infinitely diffused, material substance. Augustine tells us that the most fundamental problem he saw with this account was that God’s materiality must imply God’s divisibility (conf. 7.1; cf. 7. 5). However, through reading some ‘books of the Platonists’ at the same time as he was returning to his Christianity, Augustine came to a new account of God. This account involved five interrelated and, for Augustine, inseparable elements.

These elements are described at Confessions 7.10.16 ff. First, Augustine realised that God was the ‘light’ of Truth itself’: immaterial, eternal and everywhere and indivisibly present. God was the immaterial source of all perfections and of all Truth. Second, Augustine understood that God was distinct from all, and yet calling to and drawing all things towards Truth through a benevolent providence. Third, Augustine saw that God was Being itself. ‘Truth itself’ was identical with the real source of all existence, and thus the incorporeality and infinity of Truth itself did not mean that God was literally nothing (nihil). Fourth, Augustine reasoned that all things that are not Being itself exist only by participation in God and through the gift of Being from God. Thus, he could say of himself, ‘unless my being remains in Him, it cannot remain in me’ (conf. 7.11.17). Fifth, Augustine discovered a paradoxical relationship between the soul and God. On the one hand, the soul was immaterial and ‘above’ the material reality of the body, and when discovered to be such served as a pointer to the nature of God. On the other hand, the soul was still mutable and served only to reveal the incomparable and infinitely surpassing reality and ‘light’ of the divine.

If we were to add one more point to this list, but a point that does not appear at Confessions 7.10.16, it would be that God was ‘simple’. At Confessions 4.16.28 Augustine describes God as ‘marvellously simple and unchangeable’ (mirabiliter simplex atque incommutabilis). This is taken to imply the foolishness of trying to think of God as subject to accidental predication: imagining God as ‘having’ greatness or beauty as qualities of a divine ‘nature’ or ‘substance’. Instead, God is inseparably and eternally greatness or beauty itself. There is no division possible between being and attributes in the God who ‘simply’ is those qualities that we want to predicate of God. Divine simplicity is treated as an essential corollary of Augustine’s conception of God as immaterial, unchangeable and as Truth itself (although it is by no means simply a ‘Neoplatonic’ idea).