Colin Gunton and others criticize Augustine’s treatment of Old Testament theophanies, where Augustine concludes that it is impossible to determine which person appears in the theophany. For Gunton, the Son is the appearing-one in the Old Testament, and Augustine’s hesitation smacks of a sub-Trinitarian theology that makes the Persons interchangeable and ultimately indistinguishable.

Gunton’s complaint misses the polemical use to which Augustine puts his discussion of theophanies. As Lewis Ayres explains ( Augustine and the Trinity , 159), “Discussion of the
Old Testament theophany texts . . . occupies a good deal of space in the initial books of the De trinitate , primarily because Augustine has much invested in refuting any account in which such texts are said to reveal the Son (or the Spirit) to be by nature visible to human eyes and hence distinct in mode of existence from the Father. As is well known, Augustine rejects the
certainty of earlier traditions that it was the Word who appeared, instead building on some hints in his immediate predecessors to argue that the theophanies are a mode of communication in which one of the divine three or the Trinity as a whole speaks or is signified by the assumption of a created form.”

Ayres concludes that “In general the theophany texts make very infrequent appearances in Augustine’s corpus outside directly anti-Homoian polemical contexts.”