The First Council of Nicaea, 325

In late spring 325 something like three hundred bishops — the traditional number is 318, a figure borrowed from the servants of Abraham in Genesis — assembled in the lakeside town of Nicaea in Bithynia, at the emperor’s expense and using the imperial post to get there. It was the first time the bishops of the Christian world had met as a body, and it was possible only because the emperor had decided it should happen.

The council produced the Creed, fixed the method of calculating Easter, issued twenty canons on church discipline, and failed to settle the argument it had been called to settle.

Arius

The dispute had begun around 318 in Alexandria between the bishop Alexander and one of his priests, Arius.

Arius’s position, as far as it can be reconstructed from fragments and hostile quotation, was that the Son is the first and greatest of God’s creatures, made before time but made. The Father alone is unbegotten, uncreated, without beginning; therefore the Son, being begotten, must have had a beginning. The slogan attributed to his followers was “there was when he was not.”

The motivation was not perverse. Arius was defending the absolute uniqueness and transcendence of God against anything that looked like two gods, and he had respectable intellectual ancestry in the Alexandrian tradition. His opponents’ objection was equally direct: if the Son is a creature, then Christians worship a creature, and the God who saves is not the God who is.

The controversy spread rapidly through Egypt and Syria, partly because Arius was an effective popular communicator who set his theology to verse and, according to his enemies, to popular tunes.

Constantine’s Intervention

Constantine had become sole ruler of the empire in 324 and had adopted the Christian church as a unifying institution. A church splitting over metaphysics was not what he had in mind.

His first move was a letter to Alexander and Arius, carried by Ossius of Cordoba, treating the dispute as a trivial quarrel over words and asking both men to stop. It did not work, which is not surprising — the letter shows an emperor who had not understood what was at issue.

He then summoned a general council. The choice of Nicaea was practical: accessible by road and water, close to the imperial residence at Nicomedia, with a suitable palace.

The Council

It opened in May or June 325, with Constantine present in person — an unbaptised layman, seated on a low throne, opening the proceedings with a speech in Latin, translated into Greek.

The overwhelming majority of bishops came from the Greek east. Rome sent two priests as legates; the bishop of Rome, Silvester, did not attend. Several bishops present bore the physical marks of the persecution under Diocletian and Licinius, which had ended only twelve years earlier — a detail that conveys how abruptly the church’s situation had changed.

The Arian position was put and rejected quickly; only a handful of bishops supported it outright. The difficulty was constructing a formula that Arius’s sympathisers could not sign. Each scriptural phrase proposed — “from God,” “true God,” “the power of God” — turned out to be one the Arians could accept in their own sense.

The solution was to use a non-scriptural philosophical term: homoousios, “of the same substance” as the Father. It had the merit of being impossible to interpret in an Arian sense, and the defect of having been condemned in a previous controversy at Antioch in 268, and of being open to the opposite error — suggesting that Father and Son are the same person, or that they share a prior substance as two coins share metal.

Constantine himself appears to have pressed for homoousios, probably on the advice of Ossius. All but two bishops signed; Arius and the two were exiled.

What Else Nicaea Did

Easter. The council ruled that Easter should be celebrated by all churches on the same day, calculated independently of the Jewish calendar, on the Sunday after the first full moon following the spring equinox. The practical arrangements were left to Alexandria, which had the best astronomers. The calendrical consequences, and the later divergence between the Julian and Gregorian reckonings, are described in the Byzantine church calendar.

Canons. Twenty disciplinary canons covering the ordination of clergy, the readmission of those who had lapsed during persecution, the prohibition of self-castration, the ban on clergy lending money at interest, and the confirmation of the authority of the great sees of Alexandria, Rome and Antioch over their regions.

The Melitian schism in Egypt was addressed with a compromise that collapsed within a few years.

Why It Did Not Work

Nicaea is generally presented as the moment orthodoxy was established. In fact the following fifty-six years were mostly a period of Arian or semi-Arian ascendancy.

The reasons:

• The term was distrusted. Many eastern bishops who were not Arians disliked homoousios because it was unscriptural and open to modalist misreading. They wanted a formula that distinguished Father and Son more clearly.
• Constantine changed his mind. Within a few years he recalled Arius from exile and pressed for his readmission to communion; Athanasius, by then bishop of Alexandria, refused and was himself exiled — the first of five exiles.
• Constantius II was an Arian sympathiser. Constantine’s son, sole ruler from 353, actively promoted homoean formulas, and the council of Ariminum in 359 produced a creed so vague that Jerome wrote his famous line: “The whole world groaned and was astonished to find itself Arian.”
• The vocabulary was unsettled. Ousia and hypostasis were not yet clearly distinguished, so that the same words meant different things to different parties.

The resolution came through the work of the Cappadocian Fathers in the 360s and 370s, who clarified the terms — one ousia, three hypostases — and made the Nicene position intelligible to those who had resisted it. The Council of Constantinople in 381 confirmed and expanded the creed under Theodosius I.

The Creed

What is recited in churches as the “Nicene Creed” is actually the creed of Constantinople of 381, an expanded version with a full clause on the Holy Spirit. The Nicene original ends abruptly after “and in the Holy Spirit,” followed by a set of anathemas against Arian formulas that were dropped later.

The single most consequential later alteration is the filioque — the addition of “and the Son” to the procession of the Spirit, adopted in the Latin west and never accepted in the east. It is the doctrinal centre of the Great Schism, and the Orthodox objection is as much about the unilateral alteration of a conciliar text as about the theology.

The Legends

Nicaea attracts stories. The most durable is that St Nicholas of Myra struck Arius in the face during the debates; it first appears more than a thousand years later. Another is that the council decided which books belong in the Bible; it did not, and the canon of scripture is not mentioned in its acts. A third is that the council invented the divinity of Christ by a narrow vote; the vote was not narrow, and the belief it endorsed is attested well before 325.

The acts of the council itself do not survive. What we have is the creed, the canons, a synodal letter, and the accounts of participants and near-contemporaries — chiefly Eusebius of Caesarea, who signed the creed with visible reluctance and wrote to his own congregation explaining why.

The Creed, Then and Now

Setting the two texts side by side shows exactly what the council did and what a later council added.

Nicaea, 325 — after the clauses on the Father and the Son, it ends abruptly:

And in the Holy Spirit.

Followed by anathemas: against those who say “there was when he was not,” that he came to be from nothing, or that he is of a different substance or created or changeable.

Constantinople, 381 — the same core, with the Son’s clauses slightly reworded, the anathemas dropped, and a full paragraph added:

And in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father, who together with the Father and the Son is worshipped and glorified, who spoke through the prophets.

Plus clauses on the church, baptism, the resurrection and the age to come.

What is recited in churches is the second text. Calling it the Nicene Creed is a convenient inaccuracy; the precise name is the Niceno-Constantinopolitan Creed, and the distinction matters when discussing what Nicaea actually decided.

The filioque — “and the Son,” inserted into the procession clause — appears in Spain in the sixth century, spreads through the Frankish church, and is adopted at Rome in the eleventh. Neither council authorised it, which is the heart of the Orthodox objection described in the Great Schism.

Athanasius and the Fifty-Six Years

The standard account gives Nicaea a clean victory, and the reality was a long defeat followed by a recovery, with one man carrying much of it.

Athanasius became bishop of Alexandria in 328, three years after the council, and spent seventeen of his forty-five years as bishop in exile — five separate periods, under four emperors.

Exile	Dates	Where
First	335–337	Trier
Second	339–346	Rome
Third	356–362	Egyptian desert
Fourth	362–364	In hiding
Fifth	365–366	In hiding

The charges brought against him included murder (the alleged victim was produced alive), sorcery, embezzlement of the grain supply, and threatening to cut off Egyptian grain to Constantinople. Some were fabricated; the grain threat may not have been.

During the third exile, among the monks of the Egyptian desert, he wrote the Life of Antony, which did more than any other book to spread monasticism through the Mediterranean.

The phrase Athanasius contra mundum — Athanasius against the world — belongs to the middle decades of the century, when the emperor, most of the eastern episcopate and at times the bishop of Rome had accepted formulas he would not. That the Nicene position eventually prevailed owes a great deal to one man’s refusal to compromise over half a century, and to the Cappadocians who made it intelligible afterwards.

The Anniversary

2025 marked seventeen hundred years since the council, and the occasion produced more than commemoration.

Easter fell on the same day in the eastern and western calendars that year, which happens irregularly and was widely noted as fitting. Both Rome and Constantinople used the anniversary to renew proposals for a common date — a question Nicaea itself had legislated on and that has been unresolved since the calendar reform of 1582.

The anniversary also prompted a considerable amount of new scholarly work and several new translations of the conciliar documents, which for a general reader is the more durable result.

• The Seven Ecumenical Councils — the full sequence
• Constantine the Great — the emperor who summoned it
• The Cappadocian Fathers — who finished what Nicaea started
• The Church Fathers of Byzantium — the theological tradition
• The Christological Controversies — the next round of the argument
• Byzantine Church Government — how councils worked
• The Byzantine Church Calendar — the Easter calculation