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Of One Being With the Father: Understanding Homoousios in the Nicene Creed

Rev. C•D•F• Warrington, M.Div.
By Rev. C•D•F• Warrington, M.Div.

Ordained Minister, M.Div.

May 16, 2026

2 min read

Oil painting of the homoousios doctrine with Father and Son as one divine being in golden Byzantine theological light

One word determined the outcome of one of the most consequential theological councils in church history. Homoousios—translated in English as 'of one being' or 'of one substance'—is the term the Council of Nicaea inserted into the creed in 325 AD to settle the Arian controversy. Understanding it helps unlock why the Nicene Creed is shaped the way it is.

The Arian Problem

Arius, an Alexandrian priest, taught that the Son was the Father's first and greatest creation—divine in a derivative sense, but not coequal or coeternal with the Father. His slogan was 'there was a time when he was not.' This position had wide appeal: it seemed to preserve monotheism and made intuitive sense of texts that speak of the Son being 'sent' or praying to the Father.

The Council's Answer

The bishops at Nicaea recognized that any less-than-divine savior could not accomplish what the New Testament claimed for Christ. If Jesus is not fully God, then Christian baptism, prayer to Christ, and the Lord's Supper all become acts of creature-worship—idolatry. Only a Savior who is fully divine can bridge the infinite gap between Creator and creature. Homoousios was inserted precisely to close off the Arian loophole.

Not a Philosophical Import

Critics of Nicaea sometimes argue that homoousios is Greek philosophy smuggled into Christian theology. But the council used the word as a boundary marker, not a philosophical system. It was chosen precisely because it could not be given an Arian reading—not because it fully captured the mystery of the Trinity. The creed used philosophy's vocabulary to protect the gospel's substance.

Frequently Asked Questions

What does 'homoousios' mean in the Nicene Creed?

Homoousios is a Greek term meaning 'of the same substance' or 'of one being,' used in the Nicene Creed to describe the relationship of the Son to the Father. The creed declares that the Son is 'homoousios with the Father,' meaning he shares the same divine nature and is not a lesser or created being. This term was at the center of the Arian controversy of the fourth century, with Athanasius of Alexandria defending homoousios against the Arian alternative homoiousios ('of like substance').

Why was the word homoousios so controversial at the Council of Nicaea?

The term homoousios was controversial at Nicaea in 325 AD for several reasons: it did not appear in Scripture itself, it had previously been used by Paul of Samosata (whose theology was considered heretical), and many bishops were wary of using non-scriptural Greek philosophical vocabulary to define Christian doctrine. Some Eastern bishops preferred the ambiguous homoiousios ('of similar substance') which could be interpreted in ways compatible with Arianism. Emperor Constantine supported homoousios because it drew the clearest possible line against Arian subordinationism.

What was the Arian heresy and why did it require the Nicene response?

Arianism, associated with Arius of Alexandria (c. 256–336 AD), taught that the Son of God was the first and greatest of God's creatures — a being through whom God created everything else — but was not himself eternal or fully divine. Arius's slogan was 'there was a time when he was not,' meaning the Son had a beginning and was ontologically subordinate to the Father. The Council of Nicaea convened in 325 AD explicitly to refute this teaching, which threatened to undermine the Christian doctrines of incarnation, atonement, and salvation.

Who championed the homoousios doctrine after the Council of Nicaea?

Athanasius of Alexandria (c. 296–373 AD) was the most tenacious defender of the Nicene homoousios formula in the decades following the council. He was exiled five times by emperors sympathetic to Arianism yet consistently returned to defend the full divinity of the Son, leading to the Latin phrase Athanasius contra mundum ('Athanasius against the world'). His theological treatises, including On the Incarnation and Against the Arians, provided the doctrinal foundations for the eventual Nicene victory at the Council of Constantinople in 381 AD.

How is the homoousios doctrine reflected in the Nicene Creed as used in worship today?

In the contemporary liturgical form of the Nicene Creed, homoousios is typically rendered 'of one Being with the Father' (in older translations, 'of one substance with the Father'). This phrase appears in the second article of the creed, in the section about the Son: 'We believe in one Lord, Jesus Christ, the only Son of God...of one Being with the Father.' Every time Christians recite these words in worship, they are reaffirming the Nicene settlement against Arianism and confessing the full equality of the Son with the Father in the Godhead.

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