homoiousian

Homoiousian refers to early Christian theologians and groups who taught that the Son is of similar essence to the Father (homoiousios), as opposed to being of the same essence (homoousios) or of a different essence (heteroousios). The term appears in the mid-4th century within the wider Arian controversy surrounding the nature of the Trinity, in the wake of the Nicene Creed of 325. The Homoiousians argued that the Father and the Son share a common divine substance, but that their ousia is not strictly identical, a stance intended to affirm the divinity of the Son while avoiding an explicit assertion of numerical sameness.

The movement arose in the eastern provinces and included bishops and theologians who sought a middle way between Arius’s view and the Nicene formulation. They participated in local synods and debates that shaped the ongoing struggle over Christological language in the centuries following Nicaea. The term itself was often used by opponents of the group to label its adherents, and the label does not always reflect a single, cohesive school of thought, since individuals sometimes shifted positions in response to political and ecclesiastical pressures.

Decline followed the consolidation of Nicene orthodoxy, culminating in the First Council of Constantinople in 381, which reaffirmed the Nicene concept of consubstantiality (homoousios). While the Homoiousian position largely faded as a distinct party, it illustrates the diversity of early Christian attempts to articulate the relationship between the Father and the Son and the broader, complex process of doctrinal formation in late antiquity.