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Short description: Christian theological term and concept

Homoousion (/ˌhɒmˈsiɒn, ˌhm-/ HO(H)M-oh-OO-see-on; Ancient Greek:, from ὁμός, homós, "same" and οὐσία, ousía, "being" or "essence")[1][2] is a Christian theological term, most notably used in the Nicene Creed for describing Jesus (God the Son) as "same in being" or "same in essence" with God the Father (ὁμοούσιον τῷ Πατρί). The same term was later also applied to the Holy Spirit in order to designate him as being "same in essence" with the Father and the Son. Those notions became cornerstones of theology in Nicene Christianity, and also represent one of the most important theological concepts within the Trinitarian doctrinal understanding of God.[3]


The term ὁμοούσιον (homoousion), the accusative case form of ὁμοούσιος (homoousios),[2] was adopted at the First Council of Nicaea (325) to say that the Son is of the same substance as the Father. From its Greek original, the term was translated into other languages.[4] In Latin, which is lacking a present participle of the verb 'to be', two main corresponding variants occurred. Since the Aristotelian term ousia[5] was commonly translated in Latin as essentia (essence) or substantia (substance),[6] the Greek term homoousios was consequently translated into Latin as coessentialis or consubstantialis,[7] hence the English terms coessential and consubstantial. Some modern scholars say that homoousios is properly translated as coessential, while consubstantial has a much wider spectrum of meanings.[8] The Book of Common Prayer renders the term as "being of one substance with the Father."[9]

From ὁμοούσιος (coessential), the theological term ὁμοουσιότης (coessentiality) was also derived. It was used by Greek-speaking authors, like Didymus of Alexandria and other theologians.[10]

Pre-Nicene usage

The term homoousios had been used before its adoption by the First Council of Nicaea. Aristotle was known for using the term οὐσία (ousia) to describe his philosophical concept of Primary Substances. (Beatrice) "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." (Beatrice)

The root of homoousion is the word ousia, but the Bible refers to God’s ousia and never says that the Son is homoousios with the Father.


The Gnostics were the first to use the word homoousios. Before the Gnostics there is no trace at all of its existence.[11][12][13] They used the term homoousios "probably 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."[14]:191 It meant, "belonging to the same order of being."[14]:191

For example, Basilides, the first known Gnostic thinker to use homoousios in the first half of the 2nd century AD, speaks of a threefold sonship consubstantial with the god who is not.[15][16] The Valentinian Gnostic Ptolemy says in his letter to Flora that it is the nature of the good God to beget and bring forth only beings similar to, and consubstantial with, himself.[17] However, this Gnostic use of the term had no reference to the specific relationship between Father and Son, as is the case in the Nicene Creed.[18]

Tertullian (155-220)

Contrary to what is often claimed, Tertullian, "writing in Latin, nowhere uses any term corresponding to homoousios."[14]:190 "Tertullian ... had already used the Latin word substantia (substance) of God … For him God … had a body and indeed was located at the outer boundaries of space. … It was possible for Tertullian to think of Father, Son, and Holy Spirit sharing this substance."[14]:184 He used "the expression unius substantiae." "This has led some scholars to see Tertullian as an exponent of Nicene orthodoxy before Nicaea … But this is a far from plausible theory."[14]:184 "The word in Greek translation of Tertullian's una substantia would not be the word homoousios but mia hypostasis (one hypostasis)."[14]:193

Sabellius (fl. ca. 215)

According to Basil of Caesarea, "Sabellius used it (homoousios) … in rejecting the distinction of hypostases;"[14]:192 "in the sense of numerical sameness" (Prof Ninan). While, for Tertullian, the Father is the whole, for Sabellius, God is the whole and the Father, the Son, and the Spirit are parts of the whole:

"He considered the Father, Son, and holy Spirit, as being three portions of the divine nature." (Von Mosheim J.L. p220)

By the time the Nicene Creed was formulated, Sabellianism was already formally rejected by the church.

Origen (c. 185 – c. 253)

Origen had a significant influence on the theological thinking in the time leading up to Nicaea. "The great majority of the Eastern clergy were ultimately disciples of Origen" (Frend - In the past, it was often claimed that Origen described the Son as homoousios but recent scholarship denies that. "Origen may have rejected the term."[19]:92 "It is almost certainly right to conclude that Origen could not have spoken of the Son as homoousios with the Father."[20]:132 "Origen certainly did not apply the word homoousios to the Son and did not teach that the Son is 'from the ousia' of the Father."[14]:185 The word "consubstantial … would have suggested to him that the Father and the Son were of the same material, an idea which he was anxious to avoid."[14]:68

"There is one celebrated fragment … where Origen appears to sanction the use of homoousios. … But in its present form, this seems too closely bound to the specific interests of the post-Nicene period … to come directly from Pamphilus, let alone Origen."[20]:132-3 Rowan Williams thinks that the translator altered the text to make it appear consistent with Nicene theology.

The Dionysii

Around the year 260, there was a dispute between the bishops of Rome and Alexandria; both named Dionysius, in which the word homoousios was prominent. The dispute began between Dionysius of Alexandria and "some local Sabellians."[19]:94 Both Stead and Simonetti believe that it was those Sabellians "who had introduced the term (into the dispute)."[14]:193 In other words, they described the Son as homoousios with the Father.

The ‘Sabellians’ in Libya complained about Dionysius of Alexandria "to the bishop of Rome."[14]:191 Similar to the Sabellians, "Dionysius of Rome … claimed that Father and Son were homoousios."[19]:94 "Dionysius of Rome … found homoousios acceptable but could not tolerate a division of the Godhead into three hypostases."[14]:192 "His doctrine could only with difficulty be distinguished from that of Sabellius!"[14]:193

Dionysius of Alexandria rejected Homoousios. "It seems … likely that Dionysius of Alexandria, in a campaign against some local Sabellians, had denied the term."[19]:94 According to Basil of Caesarea, "Dionysius of Alexandria … sometimes rejected homoousios because Sabellius used it … in rejecting the distinction of hypostases."[14]:192 Simonetti "thinks that Dionysius of Alexandria had 'rejected it because for him it implied that the Father and the Son had the same hypostasis, i.e. individual existence."[14]:193

However, Dionysius of Alexandria was "persuaded by his namesake of Rome to accept (the term)"[19]:94 but he "only adopted it with reluctance"[14]:193 and only "in a general sense, meaning 'of similar nature, ‘of similar kind',"[14]:192 or "belonging to the same class,"[19]:94 "meaning that both had the same kind of nature."[14]:193 This "did not at all exclude relationships between realities that were hierarchically distinct in other ways."[19]:94-95 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.

P.F. Beatrice concludes: "The word homoousios, at its first appearance in the middle of the third century, was therefore clearly connected with the theology of a Sabellian or monarchian tendency."

Paul of Samosata

Only a few years later, "the council that deposed Paul of Samosata in 268 condemned the use of homoousios."[19]:94,[14]:193-4 "The condemnation of homoousios by this well-known council" caused "considerable embarrassment to those theologians who wanted to defend its inclusion in an official doctrinal statement in the next century."[19]:94,[14]:195 "In using the expression ‘of one substance', Paul declared that Father and Son were a solitary unit;" "a primitive undifferentiated unity."[20]:159-160 In other words, Paul used the term homoousios to say that Father and Son are one single Person, which is Sabellianism.  According to Hilary, "Our fathers (the 268-council) … repudiated homoousion" because "the word to them spelt Sabellianism."[14]:194

Adoption in the Nicene Creed

The Nicene Creed is the official doctrine of most Christian churches with regard to the ontological status of the three persons or hypostases of the Trinity: Father, Son, and Holy Spirit. The most controversial phrases in the Creed, which are also considered to be the most important parts, state that the Son was "begotten … of the substance (ousia) of the Father" and, therefore, that He is of the same substance (homoousios) as the Father.

Recent Scholarship

'Same substance' can mean both (a) one and the same substance or (b) two substances that are of the same type. In the past it was often assumed that the term homoousios in the Nicene Council means that the Son has exactly the same essence with the Father. It would follow that the Son is co-equal, co-eternal, and co-immutable with the Father.[21] However, recent scholarship now seems to agree that that is not what homoousios meant but that "it was intended to have a looser, more ambiguous sense than has in the past history of scholarship been attached to it."[14]:202 "We can therefore be pretty sure that homoousios was not intended to express the numerical identity of the Father and the Son." "While a large number of scholars have contended that the council used the term in this latter (numerical) sense, there are good grounds for questioning such a conclusion." (Erickson) Studer "also notes that the term homoousios is not used with precision at Nicaea and that later arguments for homoousios always involve constructing accounts of its meaning."[19]:238

Surprising Inclusion

The inclusion of the term homoousios (same substance) in the Nicene Creed must be regarded as most surprising. Firstly, the Bible never says anything about God’s substance. Secondly, the term was not part of the standard Christian language at the time. The term did not appear in any precious creed; not even in the draft creed prepared only a few months before Nicaea. Rowan Williams described it as "the radical words of Nicaea"[20]:236 and "conceptual innovation"[20]:234-5

Thirdly, the term is of pagan origin. R.P.C. Hanson describes them as "the new terms borrowed from the pagan philosophy of the day."[14]:846Fourthly, the Sabellian history of the term rendered it particularly suspect:

"The word homousios had not had … a very happy history. It was probably rejected by the Council of Antioch, and was suspected of being open to a Sabellian meaning. It was accepted by the heretic Paul of Samosata and this rendered it very offensive to many in the Asiatic Churches." (Philip Schaff)

For these reasons, some very powerful forces must have been at work for it to be included.

Role of the Emperor

The emperor insisted on the inclusion of the term. "The Origenists had considerable reservation about homoousios and the other phrases containing the term ousios (substance), but the emperor exerted considerable influence. Consequently, the statement was approved." (Erickson) "Constantine "pressed for its inclusion."[14]:211

Constantine even dared to explain the term to that assembly of the top leaders of the church. "It seems … that Constantine interceded on behalf of those unhappy with homoousios, insisting on the importance of understanding the term without material connotation."[19]:96 "Eusebius directly ascribes to Constantine only an emphasis on understanding homoousios without reference to material division or the sorts of change associated with corporeal existence."[19]:96

The emperor gave a non-literal meaning to the term homoousios, saying: "This phrase served only to indicate that the Son was truly from the Father."[19]:96

In the Roman culture of fourth century, the emperor had the final say in church doctrine. "If we ask the question, what was considered to constitute the ultimate authority in doctrine during the period reviewed in these pages, there can be only one answer. The will of the Emperor was the final authority."[14]:849 "The history of the period shows time and time again that ... the general council was the very invention and creation of the Emperor. General councils ... were the children of imperial policy and the Emperor was expected to dominate and control them."[14]:855

The Party of Alexander

Presumably, however, the emperor did not come up with the term homoousios by himself. Erickson explains that the Nicene Creed was put forward by Eusebius but was "revised" by "the party of Alexander," which was "favored by the emperor," who "favored the inclusion of the word homoousios." "Constantine had taken Alexander's part."[19]:89 "This imperial pressure coupled with the role of his advisers in broadly supporting the agenda of Alexander must have been a powerful force."[19]:89 "Once he (Constantine) discovered that the Eustathians … were in favour of it (homoousios) … he pressed for its inclusion."[14]:211 "Marcellus and Eustathius also seem likely to have endorsed homoousios."[19]:95

The Meaning of Homoousios

At the council, different parties understood the term differently. "Those who were broadly in the same trajectory as Alexander ... would have read them (Nicaea's terms) in a very different manner" from other delegates[19]:91

The party of Alexander, who favored the inclusion of the term, understood it as saying that Father and Son are one single Person (hypostasis). "It is unlikely that Alexander or Ossius would have chosen the term intending a simple co-ordinate sense."[19]:95 "For him (Marcellus) homoousios … meant not merely 'consubstantial' or 'of similar substance', but 'of identical being'."[14]:229-230

The Eusebians (usually but inappropriately called Arians) accepted the emperor's explanation of the term. "Eusebius tells us that once he had been assured that this phrase served only to indicate that the Son was truly from the Father he could agree even to homoousios."[19]:96

After Nicaea

Post-Nicaea Controversy

The Controversy around the 'radical words of Nicaea' continued after Nicaea. For example, the following describes one event in that conflict that occurred "probably in 326 or 327:"[19]:101

"The fifth-century ecclesiastical historian Sozomen reports a dispute immediately after the council, focused not on Arius, but … concerning the precise meaning of the term homoousios. Some thought this term … implied the non-existence of the Son of God; and that it involved the error of Montanus and Sabellius. … Eustathius accused Eusebius [of Caesarea] of altering the doctrines ratified by the council of Nicaea, while the latter declared that he approved of all the Nicaean doctrines, and reproached Eustathius for cleaving to the heresy of Sabellius."[19]:101

"This event was only one part of the conflict that now began."[19]:101 As a result of this conflict, both Eustathius and Marcellus were deposed for Sabellianism. "Eustathius lost this battle and was deposed, at some point between 326 and 331."[19]:101 "The new synod met in the summer of 336 and deposed Marcellus for holding the heresy of Paul of Samosata."[20]:80

Homoousios Disappears

After this 'Post-Nicaea Controversy, "there is a near-fifteen year absence before the creed is mentioned again."[19]:100 "Even Athanasius for about twenty years after Nicaea is strangely silent about this adjective (homoousios) which had been formally adopted into the creed of the Church in 325."[14]:58-59 "After Nicaea homoousios is not mentioned again in truly contemporary sources for two decades. … it may not be discussed simply because it was not seen as that useful or important. This lack of usage also results from the association of Nicaea with the theology of Marcellus of Ancyra. As we shall see, the language of that creed seemed to offer no prophylactic against Marcellan doctrine, and increasingly came to be seen as implying such doctrine."[19]:97 "It is … likely … that the word homoousios when it was inserted in N did not have the crucial importance in the eyes of people of that time which it was later supposed to have…. It was impossible to rid the term in the minds of many of Sabellian, if not Gnostic associations."[14]:437

Homoousios Re-appears.

After this period of absence, it was Athanasius who brought the term back into the Controversy. "Athanasius' decision to make Nicaea and homoousios central to his theology has its origins in the shifting climate of the 350s:"[19]:144 That was, in other words, about 30 years after Nicaea:

"He began to use it first in the De Deeretis and thereafter regularly in his theological works, defending it fiercely against all criticism of it. If we place De Deeretis in 356 or 357, we can perhaps see the reason for this change of policy. By then it had become abundantly clear not only that Constantius was everywhere trying to isolate Athanasius himself from ecclesiastical support both in the East and the West, but, if we assume, as seems likely, that at Aries in 353 and Milan in 355 a doctrinal formula which did nothing at all to forward the doctrine of the unity of Father and Son regarded by Athanasius as the only orthodox one, was forced upon those who attended these councils, we can imagine that Athanasius decided that he must begin a policy of defending the very words of N as a slogan or banner round which to gather."[14]:438

Sides in the Controversy

The re-introduction of homoousios into the Controversy divided the anti-Nicenes into factions:

  • The Homoi-ousians [from ὅμοιος, hómoios, "similar", as opposed to ὁμός, homós, "same, common"] (the so-called Semi-Arians) maintained that the Son’s substance is like the Father’s, but not the same.
  • Heteroousianism (or Anomoeanism) said that the Son is like the Father but His substance is unlike the Father’s.
  • Homoeanism (or Homo-ians) [from ὅμοιος, hómoios, "similar"[2]], remained the dominant emperor-supported faction, and rejected all use of ousia-terms. They declared that the Son was similar to God the Father, without reference to ousia (essence or substance). In their view, the Father was so incomparable and ineffably transcendent that even the ideas of likeness, similarity or identity in substance or essence with the subordinate Son and Holy Spirit were heretical and not justified by the Gospels. They held that the Father was like the Son in some sense but that even to speak of ousia was impertinent speculation.

Anhomoianism "was the doctrine that the Son was positively unlike the Father without further qualification." The pro-Nicenes accused their opponents of Anhomoianism but "it is doubtful if anyone ever actually held this viewpoint."[14]:572-3

Since the term homoousios, which Athanasius favored and which was ratified in the Nicene Council and Creed, was a term reported to also be used and favored by the Sabellians in their Christology, it was a term with which many followers of Athanasius were actually uncomfortable. The so-called Semi-Arians in particular objected to it. Their objection to this term was that it was considered to be "un-Scriptural, suspicious, and of a Sabellian tendency."[22] This was because Sabellius also considered the Father and the Son to be "one substance", meaning that, to Sabellius, the Father and the Son were "one essential Person", though operating in different faces, roles, or modes. This notion, however, was also rejected at the Council of Nicaea, in favor of the Nicene Creed, which holds the Father and Son to be distinct yet also coequal, coeternal, and consubstantial divine persons.

End of the Controversy

All of these positions and the almost innumerable variations on them which developed in the 4th century were strongly and tenaciously opposed by Athanasius and other pro-Nicenes, who insisted on the doctrine of homoousion or consubstantiality.

The Roman Emperor Theodosius published an edict in the year 380, prior to the Council of Constantinople, declaring that the Nicene Creed was the legitimate doctrine and that those opposed to it were heretics.[23]

Pro-Nicenes eventually prevailed in the struggle to define this as a dogma of the still-united Western and Eastern churches for the next two millennia. The term homoousion became a consistent mark of Nicene orthodoxy in both East and West. According to this doctrine, Jesus Christ is the physical manifestation of Logos (or the Word), and consequently possesses all of the inherent, ineffable perfections which religion and philosophy attribute to the Supreme Being. In the language that became universally accepted after the First Council of Constantinople in AD 381, three distinct and infinite hypostases, or divine persons, the Father, the Son, and the Holy Spirit, fully possess the very same divine ousia.

See also



  1. οὐσία. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  2. 2.0 2.1 2.2 ὁμοούσιος, ὁμοιούσιος, ὅμοιος, ὁμός in Liddell and Scott.
  3. Bethune-Baker 2004.
  4. Beatrice 2002, p. 243-272.
  5. Loux 2008.
  6. Weedman 2007.
  7. consubstantialis. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
  8. Pásztori-Kupán 2006, p. 59.
  9. Baskerville, John. "The Book of Common Prayer". Charles Wohlers. 
  10. Florovsky 1987.
  11. von Harnack, Adolf (in de), Dogmengeschichte, 1:284–85, n. 3; 2:232–34, n. 4 .
  12. Ortiz de Urbina, Ignacio (1942), "L'homoousios preniceno", Orientalia Christiana Periodica 8: 194–209 .
  13. Ortiz de Urbina, Ignacio (1947) (in es), El Simbolo Niceno, Madrid: Consejo Superior de Investigaciones Cientificas, pp. 183–202 .
  14. 14.00 14.01 14.02 14.03 14.04 14.05 14.06 14.07 14.08 14.09 14.10 14.11 14.12 14.13 14.14 14.15 14.16 14.17 14.18 14.19 14.20 14.21 14.22 14.23 14.24 14.25 14.26 14.27 14.28 14.29 14.30 14.31 Hanson, Richard Patrick Crosland (1988). The Search for the Christian Doctrine of God: The Arian Controversy, 318-381. T. & T. Clark. ISBN 978-0-567-09485-8. 
  15. of Rome, Hippolytus (in la), Refutatio omnium haeresium, 7:22, "Υἱότης τριμερής, κατὰ πάντα τῷ οὐκ ὄντι θεῷ ὁμοούσιος" .
  16. For the Gnostic use of the term, Marcovich, Miroslav (1986) (in de), Patristische Texte und Studien, 25, Berlin: W de Gruyter, pp. 290f. V,8, 10 (156); V,17,6.10 (186 f.) .
  17. of Salamis, Epiphanius (in el), Panarion, 33:7,8, "Τοῦ ἀγαθοῦ φύσιν ἔχοντος τὰ ὅμοια ἑαυτῷ καὶ ὁμοούσια γεννᾶν τε καὶ προφέρειν" .
  18. Turner, Henry E. W. "The Pattern of Christian Truth: A Study in the Relations Between Orthodoxy and Heresy in the Early Church." AMS Press, 1978, p. 161
  19. 19.00 19.01 19.02 19.03 19.04 19.05 19.06 19.07 19.08 19.09 19.10 19.11 19.12 19.13 19.14 19.15 19.16 19.17 19.18 19.19 19.20 19.21 19.22 19.23 19.24 19.25 Ayres, Lewis (2004). Nicaea and its Legacy, An Approach to Fourth-Century Trinitarian Theology. 
  20. 20.0 20.1 20.2 20.3 20.4 20.5 Williams, Rowan (2002). Arius: Heresy and Tradition (Revised ed.). Wm. B. Eerdmans Publishing. ISBN 978-0-8028-4969-4. 
  21. Fulton, W (1921), "Trinity", Encyclopædia of Religion and Ethics, 12, T&T Clark, p. 459 .
  22. St. Athanasius (1911), "In Controversy With the Arians", Select Treatises, Newman, John Henry Cardinal trans, Longmans, Green, & Co, p. 124, footn .
  23. Theodosian Code 16:2, 1 Friell, G., Williams, S., Theodosius: The Empire at Bay, London, 1994.


Further reading