A person who believes in or advocates for the heteroousia doctrine; someone who held that the Father and Son have different essences in Christian theology.
From heteroousia plus -an (noun suffix), referring to a follower or believer in the doctrine of different essences.
Heteroousians were the theological rebels of the 4th century—imagine having a religious identity defined by one Greek word meaning your god has a 'different essence,' which got you branded a heretic by the Council of Nicaea!
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