Article

Eyewitnesses to History: The Council of Nicaea in the Ancient Sources

On the 1700th anniversary of the Council of Nicaea · Part 1 of 3

Glen L. Thompson

Wisconsin Lutheran Quarterly, Vol. 122, No. 4 (Fall 2025) · Part 1 · Part 2 · Part 3

Since some recent claims have been made about what really happened at the Council of Nicaea, or whether we can actually do more than guess at the proceedings, the following study is intended to examine the firsthand accounts to see what they tell us about what took place.¹ In his Dialogue Against the Luciferians, written about 380, St. Jerome wrote that a person could “read the acts [acta] and the names of the bishops of the Council of Nicaea.”² About seventy-five years later, the church historian Sozomen, writing of events in the years after the council, relates an incident in which the two pro-Arians, Eusebius of Nicomedia and Theognis of Nicaea, “bribed the notary to whom the emperor had entrusted the custody of the documents of the Council of Nicaea and erased their [own] signatures.”³ These notices imply that some sort of minutes or official records of the famous council were kept, and that these had some circulation after 325. Unfortunately, however, they have disappeared over the centuries. What we do have are accounts and reminiscences of three individual participants—Emperor Constantine, Eusebius of Caesarea, and Athanasius of Alexandria—as well as a very brief notice from Eustathius of Antioch. We also have a letter written in the name of the council itself. Besides some additional scattered notices, historians must fill in the rest of the story of this important event from narrative accounts of various lengths by seven ancient Christian historians who lived and wrote in the century and a half following the council.

Our three main eyewitnesses make for a strange trio, and this can be illustrated by speaking of their roles at the council. Constantine had called the council, but was obviously not a normal participant. While he was present for the opening and for other parts of the proceedings, he was not a voting member. And yet it is clear that he made his presence felt, and his opinion did matter. Athanasius was a youthful deacon at the time, so he served only as an advisor, and perhaps as an amanuensis, for his bishop Alexander. Thus his influence may not have been in the official sessions of the council. Finally, we have Eusebius of Caesarea, the only one of the three who was an official participant and who appears as one of the most important figures in the proceedings. However, as we shall see, he was already under suspicion of Arianism when the council began, and was only eventually able to clear his reputation after agreeing to sign the newly composed creed. Thus, none of the three was numbered among the 250 or more “normal” participating bishops who attended.⁴ In what follows we will concentrate our attention on what the surviving writings of each of these three tell us about the council.

Constantine, the Emperor

Constantine’s early relationship to the faith and the church have been the source of endless speculation. Did he convert for political reasons? When did he see his famous vision in the sky? If he did become a true believer, when did that happen? Recent research can now allow us to construct a convincing timeline and narrative of Constantine and his relationship to the church in the two decades before the council convened. I will quickly review this timeline because these events influenced the emperor’s attitude toward and goals for the Nicene gathering.

The Roman historian Werner Eck has been instrumental in showing how Constantine ended any persecution of Christians in his territory immediately upon taking power in the far West in 306, although in some places this may have only taken effect when he physically gained control, province by province, in subsequent years.⁵ He first moved south through Germany and Gaul; it is most likely that his vision of a heavenly cross or chi-rho took place in Gaul in mid-310. He then spent some time pondering the vision’s meaning, discussing it with local Christian religious experts, i.e., bishops. He was present at Autun in the spring of 311 and may well have then consulted its bishop Reticius. He also made numerous visits to Arles in Gallia Narbonensis and built a bridge at Cologne, thus putting him in the orbit of Marinus and Maternus, the well-known bishops of these two cities.

Between his description of the vision and the 312 battle that won Rome itself for Constantine, Eusebius states that the emperor, having resolved to worship no other God, “sent for those acquainted with the mysteries of his doctrine, and inquired who that God was, and what was intended by the sign of the vision he had seen.”⁶ Hosius of Cordoba seems to have joined Constantine’s entourage as a sort of spiritual advisor or chaplain during this period as well, a position he would maintain until near the end of the emperor’s life.⁷ It was at least partially as a result of these consultations in the years leading up to the Milvian Bridge victory that Constantine became convinced that his heavenly chi-rho vision had come from the Christian God and was a mark of his favor and anointing.

After the battle, the emperor stayed for several months in Rome and became acquainted with the leaders of the Roman church, including Bishop Miltiades.⁸ With Magnentius’s defeat, Constantine now ruled the whole western empire, including North Africa, and so again he immediately issued instructions for religious tolerance and the general restoration of church property throughout these new domains as well.

After resuming his travels in early 313, however, Constantine began receiving appeals from the North African Donatists complaining that they were not getting their share of the restored property and making other accusations against the catholic Bishop Caecilian. Not satisfied with the local courts, they appealed directly to the emperor for a hearing with judges from Gaul to hear the case. Constantine agreed, appointing the three aforementioned Gallic bishops—Reticius, Maternus, and Marinus—to serve in this capacity, but further deciding that his new acquaintance, the Roman Bishop Miltiades, should chair the hearing at Rome. The bishop of Rome in turn invited an additional fifteen bishops to participate, turning the judicial hearing also into a regional church council. In October 313 it acquitted Caecilian of all charges.⁹ The Donatists then appealed to the emperor yet again, leading to a second council at Arles in 314. This time the emperor himself and more than two dozen bishops were in attendance, but again the ruling went against the plaintiffs.¹⁰ Thus, a full decade before the Council of Nicaea, Constantine was fully aware of the split church in North Africa and probably of the similar Novatian split in Rome itself. By 325 a third group would have formed in Egypt—the Melitians.

It seems that these early “councils” at Rome and Arles were intended by Constantine to be hearings in accord with the normal Roman legal process but merely chaired by church bishops instead of secular government officials. However, the presiding bishops increased the size by inviting additional bishops from the region, thus also making it into a regional or provincial church council. By 318 Constantine would officially give Christians the option of taking cases to church courts instead of secular judges; the decisions of these episcopal courts were to be legally binding and were unappealable.¹¹ So in the decade between the Milvian Bridge and Nicaea, Constantine was gradually gaining personal experience with smaller local and provincial church councils as well as the internal problems of the church. When he invoked a large church-wide council in 325, it was an attempt not only to solve major ecclesiastical issues, but to do so where he had seen smaller councils fail—and to do so in a format that was in line with the fair play and impartial justice of the Roman legal tradition.

A century ago, the texts relating to these developments, listed and numbered in chronological order as Urkunden (Urk.), were conveniently collected by H.-G. Opitz in the third volume of his Athanasius Werke. These texts with English translations are now available on the website www.fourthcentury.com together with brief introductions and the competing chronologies of Opitz, Rowan Williams, Sara Parvis, and most recently Uta Heil et al. in the continuation of the Berlin Athanasius Werke series (volume 3.3).¹² In what follows I will cite these documents using the Dok. numbering of the recent Berlin publication.¹³

Constantine’s testimony to the Nicene council comes almost entirely from the letters he issued, ten letters in particular which deal directly with the council and its aftermath and which he issued between late 324 and early 328. The earliest preserved letter of Constantine dealing directly with the Arian problem was written to both Alexander of Alexandria and Arius in a fruitless attempt to settle the dispute without a council; it was carried to Alexandria by Hosius of Cordova in late 324.¹⁴ Upon learning of this mission’s failure, the emperor issued another letter, now lost, which summoned a general council to meet at Ancyra in the summer of 325. In early 325, he sent out a third letter changing the meeting’s location to Nicaea, a letter that survives only in Syriac.¹⁵ His offer to pay for transportation costs shows that he was serious about a large attendance.

Six letters of the emperor survive that were written in the weeks and months immediately following the council. These include the fairly lengthy imperial letter addressed to Arius in which he gives his full support to the council’s Christology and appeals to Arius to recant.¹⁶ A few months later, when Arius did not respond, the emperor published an edict confirming the council’s deposition of the heretic and commanding the burning of all Arius’s writings on pain of death.¹⁷

At about the same time a letter addressed to the church in Alexandria confirmed Arius’s demise and urged the church to follow the decisions of the council, for “the collective judgment of three hundred bishops cannot be other than the doctrine of God.”¹⁸ A similar letter was directed to the church of Nicomedia, because their bishop Eusebius had “shamelessly” allied himself “to this utterly discredited falsehood” of Arius! “If,” the emperor continues, “anyone foolishly dares to praise or even to remember fondly those corrupters, he will be restrained . . . by the action of the servant of God, that is to say, by me.”¹⁹ An additional imperial letter was sent to Theodotus of Laodicea, a supporter of Arius apparently not present at Nicaea, warning him not to be further influenced by Arius and his supporters.²⁰ Two other letters of the emperor date slightly later, to late 326 and 327, respectively, and show how the emperor had still not given up on reestablishing unity within the church through the restoration of a seemingly repentant Arius.²¹

One other letter, dating to the weeks after the council, was addressed to the churches of the empire in general.²² Constantine again states clearly that his goal above all else is “that one faith, sincere love, and unvarying devotion to Almighty God be maintained among the most blessed assemblies of the catholic church” (3.17.1). As in other letters, he calls himself συνθεράπων ὑμέτερος, “your fellow-servant” (3.17.2). The emperor then devotes most of the letter to a discussion of the divergences that had long plagued the church on competing customs for celebrating Easter.²³ In his letter, Constantine asserts that on this subject also the council had reached consensus.²⁴

Constantine’s Testimony

Having sketched the situations surrounding these letters of Constantine, we can now turn to what they say specifically about the council.

In his letter changing the venue to Nicaea, the emperor states three reasons for the move: “because the bishops from Italy and the rest of the countries of Europe are coming, because of the excellent air temperature, and in order that I myself may be present as a spectator and participant [κοινωνὸς] in what will be done” (Dok. 22.2). It appears that the first goal was not achieved, for to our knowledge the only western bishops to attend were a single bishop from Italy (besides the two priests representing the bishop of Rome), one from Spain, one from Gaul, and one from Africa Proconsularis (Carthage).

In his letter to the churches (Dok. 30) written just after the council, Constantine begins by stating the rationale for the proceedings. His highest priority, he says, is that “a unity of faith, a sincerity of love, and a unanimity in devotion to the worship of Almighty God might be preserved among the most blessed assemblies of the catholic church” (Vit. Const. 3.17.1). He concluded that this required that “all of the bishops, or at least the greater part, were convened in the same place for a council where they could discuss every point of our most holy religion. So we assembled as many as possible, and I myself was also present as one of you; for I will not deny what I especially rejoice in—that I am your fellow-servant” (3.17.2).

However, he then gives very little detail about the actual proceedings: “All points were then minutely investigated, until a decision was brought to light which was found acceptable to him who is the inspector of all things, and which brought a unified agreement, leaving nothing which could cause dissension or controversy in matters of faith” (3.17.2).

It is only on the issues surrounding Easter that he elaborates further. At the council “the question about our holiest day, Easter, was also discussed, and it was resolved by common consent that everyone, everywhere should celebrate it on one and the same day” (3.18.1), that is, that all churches should follow the customs as practiced “in the city of Rome, throughout Italy, Africa, all Egypt, Spain, France, Britain, Libya, the whole of Greece, and the dioceses of Asia, Pontus, and Cilicia” (3.19.1). In between these two statements Constantine describes aspects of the problem—that according to some calculations, Easter would at times fall twice in the same year (3.18.4), and that when different dates for Easter were in use, Christians in some places would be enjoying the festivities of the post-Easter season while in other places Christians were still engaged in the repentance and fasting of Lent (3.18.6). Also, probably reflecting the discussions at the council, he claims that a proper and unified method for calculating the date of Easter and celebrating it went back to Christ and his apostles (3.18.2–3), that the council’s solution would separate the church more clearly from the Jews and their celebrations (3.18.3–4), that it would help the church remain united even though its members were so widely dispersed geographically (3.18.5), and that it was already being practiced by large regions of the church (3.19.1). He finally declares that “whatever is decided in the holy assemblies of the bishops is to be regarded as indicative of the divine will” (3.20.1)—a position he will continue to endorse in the future while at the same time having to deal with the realities of dueling councils and their often contradictory decisions.

In his letter to the Alexandrians (Dok. 29 = Decr. 38.1–9), also written soon after the council, he gives a bit more about the other debates that had taken place at Nicaea:

All points which seemed ambiguous or could possibly lead to dissension have been discussed and accurately examined. May the divine Majesty forgive the unfortunately huge number of blasphemies which some were shamelessly uttering against our mighty Savior, our life and hope, as they declared and confessed things contrary to the divinely inspired Scriptures. More than three hundred bishops, remarkable for their moderation and intellectual keenness, were unanimous in their confirmation of one and the same faith, a faith which has arisen in agreement with the truths of the Law of God. Arius alone had been misled by the devil, and was found to be the only one set on promoting this unholy mischief, first among you, and afterwards among others as well. . . . This ruling, made by the collective judgment of three hundred bishops, cannot be other than the doctrine of God, especially where the Holy Spirit has illuminated the divine will by placing it upon the minds of so many dignified persons. (4–5, 8)

The thorough discussion of the christological issues, the defense of Arian ideas by some present, the eventual agreement on the biblical doctrine, and the condemnation of Arius and his beliefs—all of these aspects of the council are attested to. And the emperor came away convinced that the collective wisdom of the council had been inspired by God himself.

Another imperial letter written soon after was addressed to the church at Nicomedia (Dok. 31 = Decr. 41.1–17), and in it Constantine describes his dealings with their bishop Eusebius who had only grudgingly signed the council’s decree. Not to be confused with the church historian and bishop of Caesarea, this Eusebius was originally the bishop of Berytus (Beirut) and became bishop of Nicomedia sometime after 314. There he became intimately acquainted with Licinius, the resident Augustus of the Eastern empire, and his wife Constantia, the sister of Constantine. Eusebius’s connection to Licinius became a deficit when the latter was defeated by Constantine in 324. In this letter, Constantine says that Eusebius had “participated in the tyrant’s savagery” and that “many circumstances clearly show us that he was totally under the patronage of the tyrant” (9). Even more pointedly, “At the moment when the clash of the opposing armies was at hand, he underhandedly sent ‘eyes’ to spy on me, and stopped just short of contributing armed assistance to the tyrant” (10).

In this letter, Constantine tries to show the people of Nicomedia that their bishop’s checkered political past was paralleled by his theological errors. He does this by telling the clergy that at the council, “at which I myself was present, as my conscience demanded,” his “sole desire was to establish complete unity, and in particular to refute and discard this question which began through the madness of Arius the Alexandrian, but swiftly gained strength through the wicked and destructive advocacy of Eusebius” (13).²⁵ He continues:

Dearest and most honored friends, how insistently (for his conscience had convicted him) and how shamelessly did this man Eusebius ally himself to this utterly discredited falsehood! He secretly sent others as messengers to solicit me, and he asked for my support in some degree, because he was afraid that if he was detected in such a great sin, he would be expelled from his honorable office. God is my witness of this (may he continue his goodness to me and to you), since Eusebius perverted my judgment and got round me in an underhanded way, as you also will come to know. At that time, everything was done as he wanted, and he concealed all his evil intentions in his own mind. (14)

These backdoor attempts at influencing the emperor must have been carried out by Eusebius and the other allies of Arius either just before the council or, more likely, during the council’s debates. The fact that Eusebius “concealed” his true position is supported by other ancient writers.²⁶ Finally, even after the council had ruled on the matter, Eusebius and his associate Theognis of Nicaea continued to support Arius and the others who had been anathematized but were still “fanning into flames the fires of disunity” (15), and therefore Constantine had them banished as well (16).²⁷

These descriptions by Constantine are precious since they were penned in such proximity to the events. We only catch glimpses of those events within the larger literary contexts of the fifth-century church historians who are not always impartial either. Yet, as we will see, what the emperor says fits well into the picture given us by our other eyewitnesses.

We should perhaps also note one thing that is not found in Constantine’s own testimony or that of any other of our eyewitnesses. In recent decades it has often been claimed that Constantine influenced the council to adopt a specific canon of the NT. This is based loosely on a letter in which Constantine asks Eusebius of Caesarea to prepare fifty luxury copies of the Holy Scriptures (τῶν θείων γραφῶν) for the expanding church in his new capital of Constantinople.²⁸ Eusebius puts this letter in book 4, a sort of appendix to his imperial biography, together with other letters showing the emperor’s concern for the church, thus making it difficult to date. However, since the letter confirms that the new capital was expanding rapidly, the letter must surely date to several years after its dedication in 330. It also makes no specific mention of the NT or any canonical issues, or of Nicaea. Socrates Scholasticus, compiling his Church History a century later, placed the letter immediately after the four letters of Constantine from the end of the council (Doks. 25, 28–30) with the simple heading “Another letter.” This apparently opened the door for the false claims that the council discussed and decided the NT canon with Constantine’s input. There is nothing in the ancient sources to support this.

Continued in Part 2 →

Notes

¹ Along the way we will also cite the church histories of Socrates (Scholasticus), Sozomen, Theodoret, Rufinus, Philostorgius, and the so-called Anonymous Church History (CPG 6034, often erroneously attributed to Gelasius of Cyzicus). Unless otherwise specified, this article will always refer to the church history (Hist. eccl.) of each author, and we will provide only book and section numbers. For Eusebius we will distinguish between his Church History (Hist. eccl.) and his Life of Constantine (Vit. Const.).

² This comment comes in ch. 20, where Jerome is arguing that the Luciferians should show forgiveness to their repentant opponents. He then cites Nicaea in support, since the Arians were allowed to repent and be readmitted.

³ Εὐσέβιος ὁ Νικομηδείας ἐπίσκοπος καὶ Θεόγνιος ὁ Νικαίας παραπείσαντες τὸν ὑπὸ τοῦ βασιλέως ἐπιτραπέντα φυλάττειν τὴν γραφὴν τῆς ἐν Νικαίᾳ συνόδου ἀπήλειψαν τὰς ἑαυτῶν ὑπογραφὰς (Eccl. hist. 2.21.6).

⁴ On the number of bishops, see below.

⁵ See Werner Eck, “Eine historische Zeitenwende: Kaiser Constantins Hinwendung zum Christentum und die gallischen Bischöfe,” in Konstantin der Grosse: Kaiser einer Epochenwende, ed. F. Schuller and H. Wolff (Lindenberg: Kunstverlag Josef Fink, 2007), 69–94. For Constantine’s movements before Nicaea, see T. D. Barnes, The New Empire of Diocletian and Constantine (Cambridge, MA: Harvard University Press, 1982), 68–76.

⁶ τοὺς τῶν αὐτοῦ λόγων μύστας ἀνεκαλεῖτο, καὶ τίς εἴη θεὸς [οὗτος] ἡρώτα τίς τε ὁ τῆς ὀφθείσης ὄψεως τοῦ σημείου λόγος (Eusebius, Vit. Const. 1.32).

⁷ Eusebius, Hist. eccl. 10.6.1–3.

⁸ He entered the city on 29 October 312 and was in Milan by mid-January of 313. Richard Krautheimer (Corpus basilicarum christianarum Romae [Pontificio istituto di archeologia cristiana, 1937–77], 5:10, 90), John Curran (Pagan City and Christian Capital: Rome in the Fourth Century [Oxford University Press, 1999], 93–95), and others have argued that a dedicatio—a ceding to the church of the imperial Lateran property in Rome for the purposes of constructing a Christian basilica—took place on 9 November 312, just two weeks after Constantine’s entry into Rome. In essence, this was the emperor’s ex voto offering of thanksgiving for his victory.

⁹ Optatus of Milevis, Against the Donatists 1.23.

¹⁰ Canons survive, as well as a letter from the council to Sylvester which also lists some of the bishops present (both ed. C. Munier, Concilia Galliae a.314–a.506 [Brepols, 1963], 4–13).

¹¹ Theodosian Code 1.27.1. For commentary on this development, see John Dillon, The Justice of Constantine: Law, Communication, and Control (Ann Arbor: University of Michigan Press, 2012), 147–54.

¹² The original work was H.-G. Opitz, Athanasius Werke 3.1.1–2 (Berlin: de Gruyter, 1934). Since most of the documents are undated, others have since proposed alternatives to the chronology proposed by Opitz; see especially Rowan Williams, Arius: Heresy and Tradition, rev. ed. (Grand Rapids: Eerdmans, 2002); Sara Parvis, Marcellus of Ancyra and the Lost Years of the Arian Controversy, 325–345 (Oxford: Oxford University Press, 2006); H. C. Brennecke, U. Heil, et al., Dokumente zur Geschichte des Arianischen Streites (Athanasius Werke 3.1.3 [Berlin: de Gruyter, 2007]). Heil’s analysis is on pp. xix–xxxviii. We will follow the chronology of this volume and cite each item according to the Dokumenten (Dok.) number they assign to it. See the overview chart at https://www.fourthcentury.com/documents-of-the-early-arian-controversy/.

¹³ Note that while the recent Athanasius Werke 3.1.3 volume gives translations for all the Dokumenten, they do not supply the original texts except for the few additional items they add to Opitz’s original list. The original texts with side-by-side translations are available online on the www.fourthcentury.com site.

¹⁴ Dok. 19 = Eusebius, Vit. Const. 2.64.

¹⁵ Dok. 22. Eduard Schwartz back-translated the surviving Syriac text into Greek in his “Zur Geschichte des Athanasius, VI.,” in Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen, Philologisch-historische Klasse (Göttingen: Lüder Horstmann, 1905), 289; reprinted in Eduard Schwartz, Gesammelte Schriften (Berlin: de Gruyter, 1959), 3:155–56.

¹⁶ Dok. 27 = Athanasius, Decr. (Defense of the Nicene Definition) 40. His plea to Arius is found in section 17: “good Arius, . . . do you not understand that you have been barred publicly from God’s church? You are lost (be well assured), unless, having regard for yourself, you condemn your present folly.”

¹⁷ Dok. 28 = Decr. 39.1–2.

¹⁸ Dok. 29 = Decr. 38.1–9; the citation is from sec. 8.

¹⁹ Dok. 31 = Decr. 41.1–17; the citations are from sec. 14, 17.

²⁰ Dok. 32 = Decr. 42.1–3.

²¹ The first of these letters, Dok. 33, seemingly from later in 327, is preserved only by Socrates (Hist. eccl. 1.25.7–8). It grants permission for the exiled Arius to travel to the emperor’s court to seek possible rehabilitation. It appears that Arius did convince the emperor of his change of heart and so the emperor wrote to Alexander (Dok. 37, preserved only in the Anonymous Church History) asking that, in the interest of unity, he receive the repentant man. It appears that by the time the letter arrived, Alexander had died. Arius’s status would remain in limbo until his death some years later.

²² Dok. 30 = Eusebius, Vit. Const. 3.17–208.

²³ In Syria, Mesopotamia, and other regions of the East, traditional Jewish methods were followed, while the Latin West and Egypt used a method that ensured Easter would always fall on a Sunday. Discussions of greater or lesser intensity had taken place for nearly two centuries, with no accord reached.

²⁴ In the letter he urges all the people “to accept the reasoning which has proved itself to be sound, and to establish this observance of the most holy day” (12). As with the Arian situation, progress had indeed been made, but the Celtic church, for example, would still be out of sync with the Latin church on this issue for another three and a half centuries.

²⁵ After Arius was sent into exile following Nicaea, Eusebius of Nicomedia inherited the leadership of the partisans of Arian-type theology in the eastern empire, so much so that the group would become known as “the Eusebians.” See David M. Gwynn, The Eusebians: The Polemic of Athanasius of Alexandria and the Construction of the “Arian Controversy” (Oxford: Oxford University Press, 2007).

²⁶ Perhaps most telling is that Philostorgius, writing several generations later from a Eunomian christological perspective, agreed that Eusebius and the other Arians who signed the creed at Nicaea did so duplicitously (J. Bidez, ed., Philostorgius: Kirchengeschichte, GCS 21 [Berlin: de Gruyter, 1981], 1.9).

²⁷ The previously mentioned letter of Constantine to Theodotus of Laodicea (Dok. 32), written in this same time frame, repeats the same point: “You can easily learn this from what has happened to Eusebius and Theognius. They treated the most holy religion with abusive, drunken violence, and when they were in the private company of their gang of robbers, they continued to defile the name of our Savior God even after they had been granted pardon. They ought to have corrected their former error, especially after complete agreement was reached at the council. But instead at this time they were discovered to be standing fast in their former absurdities” (1).

²⁸ Eusebius, Vit. Const. 4.36. Κατὰ τὴν ἐπώνυμον ἡμῖν πόλιν; it is also found in Socrates, Hist. eccl. 1.9; Theodoret, Hist. eccl. 1.16.1–4; Anonymous Church History 3.4.1–5; Nicephorus, Hist. eccl. 8.27; and Cassiodorus, Hist. tripart. 2.16.1–5.