homoiousian

Christianity

Also known as: homoiousios

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June 29, 2026

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The term "homoiousian" refers to a belief within early Christianity that was central to Christological debates in the 4th century. Adherents of this view believed that Jesus Christ was of a substance similar to, but not the same as, God the Father. This position contrasted with the "homoousian" doctrine, which asserted that the Son and the Father were of the same substance.123

The controversy surrounding these beliefs led to the First Council of Nicaea in 325 CE. This council condemned Arianism, a related doctrine that denied Christ's full divinity, and affirmed the homoousian belief that Christ and the Father are of one substance. The Nicene Creed, developed at this council and later affirmed, became a definitive statement of orthodox Christian belief regarding the Trinity.24

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George of Laodicea
…the principal champions of the homoiousian, or moderate Arian, theological position of the early Christian church.
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…the principal champions of the homoiousian, or moderate Arian, theological position of the early Christian church.
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Arianism
History of controversy and conflict
Constantius at first supported those homoiousians but soon transferred his support to the homoeans, led by Acacius, who affirmed that the Son was “like” (homoios) the Father. Their views were approved in 360 at Constantinople, where all previous creeds were rejected; the term ousia (“substance” or “stuff”) was repudiated; and…
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Constantius at first supported those homoiousians but soon transferred his support to the homoeans, led by Acacius, who affirmed that the Son was “like” (homoios) the Father. Their views were approved in 360 at Constantinople, where all previous creeds were rejected; the term ousia (“substance” or “stuff”) was repudiated; and…
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semi-Arianism
…is “of similar substance” (homoiousios) with the Father but not of one substance (homoousios) with him. This doctrinal controversy, revolving around two words distinguished by a single iota (ι), gave rise to the popular expression, “It makes not one iota of difference.” To Orthodox Christians, however, the iota was…
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…is “of similar substance” (homoiousios) with the Father but not of one substance (homoousios) with him. This doctrinal controversy, revolving around two words distinguished by a single iota (ι), gave rise to the popular expression, “It makes not one iota of difference.” To Orthodox Christians, however, the iota was…
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