Anomoeanism

Extreme Arianism: the Son is unlike the Father in essence — the most radical wing of the Arian controversy.

The Anomoeans (led by Aetius and Eunomius) held that the Son is unlike the Father even in will and action. Eunomius argued that the divine essence is fully comprehensible as 'unbegottenness,' making the begotten Son of a completely different and inferior essence. Condemned at Constantinople I (381 AD). Eunomius's claim that God's essence is fully comprehensible was itself a significant theological error, provoking Basil's response that the divine essence is incomprehensible.