In their theological debate with Eunomius of Cyzicus, it is well-known that the Cappadocians strongly disputed their opponent’s claim that “God knows no more of His own substance than we do” (Socrates, Church History IV.7) by appealing to the absolute incomprehensibility of God’s essence (e.g., Gregory of Nazianzus, Or. 28). What is less often recognized is that these Church Fathers were not alone in their appeal to divine incomprehensibility, even if they were unique in their formulations and the context of their debate.
This paper aims to supplement our understanding of the Cappadocian doctrine by locating it within the broader 4th-century context, particularly in the early stages of the “Arian” controversy. Though Arius was no Eunomius and allowed some understanding of divine incomprehensibility, he was still refuted by appeal to this teaching (e.g., Alexander of Alexandria, Letter to Alexander 20-22). By looking to the deployment of this doctrine in this early controversy, I will examine how it was understood and utilized in early pro-Nicene thought before comparing this to its later use by the Cappadocians. Finally, based on this analysis, I will briefly address how Protestants might retrieve this doctrine and what role it might play in theological debate today.