According to the Nicean Creed, Jesus Christ is said to be:

Light of Light, true God of true God, begotten and not made; of the very same being (ὁμοούσιον) of the Father, by Whom all things came into being, in heaven and on earth, visible and invisible.

φῶς ἐκ φωτός, Θεὸν ἀληθινὸν ἐκ Θεοῦ ἀληθινοῦ, γεννηθέντα οὐ ποιηθέντα, ὁμοούσιον τῷ Πατρί, δι' οὗ τὰ πάντα ἐγένετο

How was the idea of homoousion developed, and when was this term used prior to the Council of Nicea?


3 Answers 3


This seems to have been prompted by Greek Philosophy beginning about 600 BC. This is most pronounced in the teachings of Plato, specifically his Theory of Forms in Plato's cave allegory.


In Plato's theory, εἶδος (eidos) represents the "Visible Form" while, μορφή (morphē) represents the "shape". Additionally, within Greco-Roman philosophy, there were also the φαινόμενα (phainomena), "appearances" which underwent significant philosophical discussion.

In Plato's allegory, Plato asks Glaucon to imagine a prisoner in a cell in a dungeon or cave. Out of view of the prisoner is a light source. This light source illuminates an object - again out of view of the prisoner. The prisoner in the cave is only able to see the shadow cast by the object:

Allegory of the Cave

In terms of the Allegory, the εἶδος (eidos) is the object or vase while the μορφή (morphē) is the projected image of the object, or the shadow of the vase.

As Wikipedia notes,

The English word "form" may be used to translate two distinct concepts that concerned Plato—the outward "form" or appearance of something, and "Form" in a new, technical nature, that never

...assumes a form like that of any of the things which enter into her; ... But the forms which enter into and go out of her are the likenesses of real existences modelled after their patterns in a wonderful and inexplicable manner....

The objects that are seen, according to Plato, are not real, but literally mimic the real Forms.

So in terms of God, the form of God as it appears to us (where we are the prisoner in Plato's cave) is the μορφή (morphē). This term acknowledges that our ability to view God is imperfect, and we are not capable of truly seeing God fully and directly. In trinitarian thought, the incarnation of Jesus might be thought of in some contexts as μορφή (morphē) - as Jesus, that was how God was able to appear to us.

Conversely, God's true form could be thought of as εἶδος (eidos). It holds the concept of God's true and actual form which we lack the ability and perspective to view properly due to our humanly limitations.

The Bible books of John and Philippians appear to reference this as do many other passages, I am sure:

who, though he was in the form [morphe] of God, did not count equality with God a thing to be grasped (Philippians 2:6 ESV).

And the Father who sent me has himself borne witness about me. His voice you have never heard, his form [eidos] you have never seen, (John 5:37 ESV)

Similarly, the Holy Spirit at Pentecost might be thought to be the φαινόμενα (phainomena) of God.

So, how do we get from form to substance?

The obvious problem for the philosopher here is that if Jesus is merely the form (morphē) of God, then he is not truly God. If Jesus is form (morphē) then he is not εἶδος (eidos). If the holy spirit is a φαινόμενα (phainomena) then she is not εἶδος (eidos).

This presents a problem for the Trinitarian scripturally, with Jesus's claims to be God.

This can then easily be corrected by asking "well, what if Jesus, the Holy Spirit and God are different forms, but are all of the same substance?" What if Jesus is but is a different form (morphē) of God, but is ὁμοούσιος (Homooúsios) as God?

Vs-à-vis Gnosticism

While Aristotle was known for using the term οὐσία to describe his philosophical concept of Primary Substances, the term ὁμοούσιος (Homooúsios) is first used by the Gnostics to describe their doctrine of Emanations, a concept that supported the idea of Aeons - a Panentheistic idea that we all worship the same God which simply appears in different forms (but these gods are also ὁμοούσιος [Homooúsios] or of the same substance as God). In contrast Sabellianism believed that God was singular and not triune, while Gnosticism taught god was polyune. According to Sabellianism, God is only one indivisible being and nothing can be of the same substance as God - he can only be taking on a different role or mode when he acts as the Holy Spirit or as Jesus.


From this context, we can easily see how we arrive at the Arian Controversy after this issue was raised and brought to the public attention by the Gnostics and philosophers. With this background in place, it is clear that when the language of Plato's Theory of Forms is used to describe Jesus as a form of God, it lends itself to the idea that Jesus is not God, but is merely a shadow or projection of God - not God himself. The language and concept of οὐσία therefore became necessary for the Trinitarians to explain both how Jesus could be both a form of God and BE God.

  • Also see: christianity.stackexchange.com/a/50588/14525 Feb 2, 2017 at 4:17
  • Thank you for the answer James. (+1) definitely. I didn't know Plato's cave was relevant. But could you explain what the gnostics have to do with this? I thought the gnostics were heretical groups, so what is their connection with the trinitarians? Three different forms as one god sounds exactly like Sabellianism.
    – Cannabijoy
    Feb 2, 2017 at 13:43
  • @anonymouswho I have updated this answer to more directly address your question about Gnosticism and Sabellianism. Note that this answer largely sources from here Feb 5, 2017 at 8:18
  • This looks great James. Thank you. Answer accepted and bounty is yours!
    – Cannabijoy
    Feb 6, 2017 at 6:39

The root of ὁμοούσιον ("one substance") is the word οὐσία ("substance"). The other key word in the Nicene Creed is "hypostasis", which mentioned together with "substance" in the anathemas:

But as for those who say, There was when He was not,
and, Before being born He was not,
and that He came into existence out of nothing,
or who assert that the Son of God is of a different hypostasis [ὑπόστασις]
or substance [οὐσία],
or created,
or is subject to alteration or change
- these the Catholic and apostolic Church anathematizes.

In New Testament usage, substance/οὐσία is translated as "goods" (Luke 15:12) or "substance" (Luke 15:13) in the King James Version, and in modern versions as "property" (RSV, ESV), "estate" (NASB, NIV), and "wealth" (NIV). Hypostasis/ὑπόστασις in the KJV is related as "confidence" (2 Corinthians 9:4, 11:17 and Hebrews 3:14), (confusingly) "substance" (Hebrews 11:1), and "of [his] person" (Hebrews 1:3). Modern versions also render the word as "confident/confidence" (RSV, ESV, NASB, NIV), "conviction" (RSV, NIV), "assurance" (ESV, NASB), as well as "of [his] nature" (RSV, ESV, NASB) and "of [his] being" (NIV).

These two words have very particular theological meanings, however, in the context of the Nicene-Creed, where they were used not only to combat the Arian heresy, but also to clarify the very nature of the Trinity. Michael Pomazansky attempts to explain the development of both terms in the Nicene context as follows:

In earliest Christian times, until the Church’s faith in the Oneness of Essence and the equality of the Persons of the Holy Trinity had been precisely formulated in strictly defined terminology, it happened that even those Church writers who were careful to be in agreement with the universal consciousness of the Church and had no intention to violate it with any personal views of their own, sometimes, together with clear Orthodox thoughts, used expressions concerning the Divinity of the Persons of the Holy Trinity which were not entirely precise and did not clearly affirm the equality of the Persons.

This can be explained, for the most part, by the fact that in one and the same term some shepherds of the Church placed one meaning and others, another meaning. The concept of “essence” was expressed in the Greek language by the word ousia, and this word was in general understood by everyone in the same way. Using the word ousia, the Holy Fathers referred it to the concept of “Person.” But a lack of clarity was introduced by the use of another word, “Hypostasis.” Some signified by this term the “Persons” of the Holy Trinity, and others the “Essence.” This circumstance hindered mutual understanding. Finally, following the authoritative example of St. Basil the Great, it became accepted to understand by the word Hypostasis the Personal attributes in the Triune Divinity.

Orthodox Dogmatic Theology, p. 94-95

  • Thank you Dialogist. This is a great answer, except I'm only looking for usages of the term ὁμοούσιον and not the words associated with it. The actual word itself is not in the NT (but that's okay because neither is trinity, or eternally begotten, or incarnation, or God the Son, or consubstantial, ect), and I'm wondering how this term became accepted as Christian doctrine.
    – Cannabijoy
    Sep 1, 2016 at 13:56
  • I do think the root word is what's important here, but thanks. That is what had a novel meaning imputed to it.
    – user22553
    Sep 1, 2016 at 13:58

Homoousios - What does it mean?

This is a summary of my article on the meaning of the term homoousios.

In this summary, I removed all the quotations and provided only the conclusions to enable the reader may see the big picture. This is, in my view, a crucial subject that puts a new perspective on the entire fourth-century Arian Controversy.

These conclusions will seem heterodox to the average Christian but they're based entirely on the writings of recent world-class scholars. Over the last century, after ancient documents have become more readily available, scholars have realized that the traditional textbook account of the Arian Controversy is a complete travesty. For a discussion, see - The Revised Scholarly View.

The Nicene Creed was first formulated at the Council of Nicaea (AD 325). It says that the Son

  • Was begotten of the substance (ousia) of the Father and that
  • He is of the same substance (homoousios) as the Father.

Alternative Meanings

‘Same substance’ has two possible meanings:

  • One Substance - In the traditional account of the Arian Controversy, the Trinity doctrine has existed right from the beginning. In the Trinity doctrine, God is one Being (ousia) but three Persons (hypostases). Therefore Trinitarians claim that the word homoousios in the Creed means that Father and Son are one single substance (one Being).

  • Two Substances – The alternative meaning is two substances (two Beings) with equal divinity.

But recent scholarship, however, seems to agree that homoousios does not have either of these two meanings. They say that it was intended to have a looser, more ambiguous sense.

Two Views at Nicaea

A minority was able to dominate the Nicene Council because they had the support of the emperor. Consequently, they were able to put the term homoousios in the Creed, despite the objections of the majority. So, we must distinguish between two meanings:

  • The meaning the minority intended with the term and
  • The meaning the majority assigned to it that enabled them to accept the Creed.

To determine those meanings, consider what homoousios meant (1) before, (2) during, and (3) after Nicaea:

Homoousios before Nicaea

In Greek Philosophy, Aristotle used the term οὐσία (ousia) to describe his philosophical concept of Primary Substances.

In Paganism, particularly in the theological language of Egyptian paganism, the word homoousios meant that the Nous-Father and the Logos-Son, who are two distinct beings, share the same perfection of the divine nature.

The Bible never talks about God’s ousia and never says that the Son is homoousios with the Father.

Gnostics used the term homoousios to indicate that the lower deities are of the ‘same ontological status’ or ‘of a similar kind’ as the highest deity from whom they were derived or emanated. But Gnostics were not really Christians and they did not use the term to describe the Son's relationship to the Father.

Tertullian (155-220), writing in Latin, nowhere uses any term corresponding to homoousios. He used “the expression unius substantiae.” In the past, it was often claimed that this is equivalent to homoousios but it means ‘mia hypostasis’ (one hypostasis).

Sabellius (fl. ca. 215) used the term homoousios in his theory in which the Father, the Son, and the Holy Spirit are one and the same Person (hypostasis). In other words, he said there is only one substance.

Origen (c. 185 – c. 253) did not apply the word homoousios to the Son and did not teach that the Son is 'from the ousia' of the Father, despite claims in the past to the contrary. There is one celebrated fragment where Origen appears to sanction the use of homoousios, but the translator probably altered the text to make it appear consistent with Nicene theology.

Libyan Sabellians, around the year 260, described the Son as homoousios with the Father. They were meaning that the Father and Son are one single hypostasis (Person). Consequently, the Son does not have a real distinct existence.

Dionysius, bishop of Rome, agreed with the Libyan Sabellians that Father and Son were homoousios. He, effectively, was a Sabellian. His doctrine could only with difficulty be distinguished from that of Sabellius.

Dionysius, bishop of Alexandria, opposed those Libyan Sabellians and rejected the term because Sabellius used it in rejecting the distinction of hypostases. But those ‘Sabellians’ in Libya complained to the bishop of Rome who persuaded Dionysius of Alexandria to accept the term. However, the latter only adopted it with reluctance and only in a general sense, meaning ‘of similar kind'. In other words, for him, the term did not mean that Father and Son are one and the same or even that they are equal.

Paul of Samosata was deposed only a few years later in 268. Paul used the term to say that Father and Son were ‘a primitive undifferentiated unity’. That same council also condemned homoousion because it spelt to them Sabellianism.


Before Nicaea, the term homoousios was used only by Sabellians. They used it to say that Father and Son are one single Person. In their view, the Son has no real distinct existence. The only non-Sabellian to use the term was Dionysius of Alexandria, but he only adopted it with reluctance and only in a general sense, meaning 'of similar nature'.

Therefore, to determine the meaning of the term in the Nicene Creed, one needs to identify the theology of the party that was able to force the inclusion of the term in the Creed.

Homoousios at Nicaea

A Surprising Innovation

The inclusion of the term in the Nicene Creed must be regarded as a surprising innovation because it is not a Biblical term, was not part of the standard Christian language at the time, but was borrowed from the pagan philosophy of the day. Furthermore, the Sabellian history of the term rendered it particularly suspect. For these reasons, some very powerful force must have been at work to ensure its inclusion.

The Emperor’s Role

That powerful force was the emperor. In the fourth century, the general councils (the so-called ecumenical councils) were called and controlled by the emperors. They were the tools by which the Emperor ruled the church. In the Roman culture, the emperor had the final say in church doctrine.

Consistent with this principle, at Nicaea, the emperor not only proposed but also insisted the inclusion of the term. Constantine even dared to explain the meaning of the term.

Alexander's Party

However, Constantine did not come up with the term homoousios by himself. The term was favored by the minority party of Alexander. That party was able to dominate and insert the term in the Creed because the emperor took their side.

The leaders of that party were:

  • Alexander himself,
  • Ossius - the chairperson, as the emperor's representative, and
  • the two leading Sabellians, Eustathius and Marcellus.

However, all four of them were Sabellians. The Nicene Creed, therefore, was the work of a Sabellian minority.

How was Homoousios understood?

How, then, did the delegates to the Council understand the term homoousios?

  • The Sabellians intended to term to mean that the Father and Son are one single Person (one hypostasis). Consequently, after Nicaea, the Sabellians claimed the Creed as support for their doctrine.

  • The majority, on the other hand, was able to agree to the Creed because they had accepted the emperor’s explanation that it simply means that the Son is truly from the Father. With that understanding, it does not mean that Father and Son are one Person or even that they are equal. However, after the council meeting, that same majority opposed the Creed because they thought it taught Sabellianism.

So, in conclusion, all parties understood the term homoousios in a Sabellian sense.

Homoousios after Nicaea

Post-Nicaea Correction

After Nicaea, the conflict over the term homoousios continued for a few years. I refer to it as the ‘Post-Nicaea Correction’ because it corrected the distortions caused at Nicaea by the sway of the emperor. This 'correction', therefore, should be regarded as part of the Nicene event.

By this time, Arius was out of the picture. Alexander also retired a year after Nicaea. The conflict was specifically between the Eusebian majority and the two leading Sabellians; Eustathius and Marcellus. As a result of this conflict, both of them were deposed for Sabellianism:

Not Mentioned

After the ‘Post-Nicaea correction’, Nicaea and homoousios were mentioned again for about 20 years. It was not regarded as useful or important.

During this period when homoousios was not mentioned, two councils were held that are important because they reveal the true views of the delegates at Nicaea.

  • East - At first, the ‘West’ was on the fringes of the Arian Controversy. For example, the delegates at Nicaea were drawn almost entirely from the East. So, what the delegates to Nicaea really believed when not compelled by the emperor can be seen in the Eastern Dedication Creed formulated in 431. It shows that they regarded the Nicene Creed as dangerously Sabellian.

  • West - Two years later, in 343, the West held a council at Sardica. The 'West' is generally known for being defenders of Nicaea, but the creed from that council explicitly says that Father and Son are one Person, which reveals the Sabellian preference of the West at this time. This is confirmed by their vindication of Marcellus, the main Sabellian at the time, in the year 431.

Neither of these councils used the term homoousios.

Athanasius re-invented Homoousios.

That would have been the end of homoousios. However, in the 350s – 30 years after Nicaea, Athanasius brought it back into the Controversy. Athanasius is known as the main defender of the Nicene Creed and homoousios during the years after Nicaea but, as another article shows, Athanasius also was a Sabellian. In his view, the Son is part of the Father. Athanasius, therefore, re-invented homoousios to defend his Sabellian theology; not to defend the Nicene Creed.

Anti-Sabellian Front

In the 350s, after homoousios had become a key factor in the Controversy, and the West attacked the East with it, the Eusebians (the so-called Arians) were divided into several factions with respect to homoousios, but they formed a united front against the Sabellian thrust of the Western church. This shows that the main enemy remained Sabellianism.

Meletian Schism

In the 360s and 370s, in what is known as the Meletian Schism, there were two factions in the pro-Nicene camp:

  • The ‘one hypostasis’-side (the Sabellians) was led by bishop Damasus of Rome and by Athanasius.
  • The ‘three hypostasis’-side was led by Basil of Caesarea. He regarded the Father, Son, and Holy Spirit to be three distinct Beings (substances) but he claimed that they have exactly the same type of substance. See – Basil.

Final Conclusions

Before Nicaea, the only Christian theologians who favored the term were Sabellians.

At Nicaea, a Sabellian minority was able to insert the term in the Creed, against the wishes of the majority, because the emperor took Alexander's part.

During the decade after Nicaea, the main drivers of the term homoousios were removed from their positions. There-after, the term was not mentioned again until Athanasius brought it back into the dispute about 30 years after Nicaea; not to defend the term as such, but to defend his own Sabellian theology.

The West accepted Athanasius’ explanation because the West was traditionally Sabellian.

Basil of Caesarea later accepted homoousios. However, he opposed Athanasius’ understanding of the term and explained it in a generic sense.

Therefore, before, during, and after Nicaea, the advocates of the term homoousios were Sabellians. It must be understood in a Sabellian sense.


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