An empire that had spent three centuries not caring what anyone believed spent the fourth century legislating about a single Greek word.
The previous lesson left Constantine with a church inside his government and a doctrinal quarrel he had convened a council to settle. This lesson follows what the settlement did not settle, and traces the consequence that outlasts everything else in this course: an institution with its own hierarchy, its own law, its own revenues and its own claim to authority, operating inside the Roman state and eventually outliving it in the west.
One word
The dispute Constantine walked into had been started by an Alexandrian priest, Arius, who argued that if the Son was begotten by the Father, then there was a time when he did not exist, so he is the first and highest of created things rather than God in the same sense as the Father. This was not a quibble. It concerned whether Christians worshipped one God or something closer to two, and whether the figure at the centre of their cult was divine or exalted.
The council at Nicaea in 325 answered with a creed containing the word homoousios, meaning of the same substance as the Father. It was a decisive word and an unfortunate one, because it appeared in no scripture, had been used by heretics, and meant different things to Greek and Latin speakers. In the following decades a rival formula circulated, homoiousios, of like substance, differing by a single letter, and the contrast became the standard illustration of theological hair-splitting.
Two honest qualifications. The one-letter contrast belongs to the 350s rather than to Nicaea, so quoting it as the substance of the original dispute compresses thirty years. And the number of bishops present, traditionally 318, is a figure borrowed from the book of Genesis; contemporary estimates run nearer 250 to 300, and fewer than ten came from the Latin west, which matters for how the western church later regarded a decision taken almost entirely in Greek.
Fifty years of imperial theology
Nicaea did not end the argument; it made the emperor a party to it. Constantine himself recalled Arius from exile within a few years, and was baptised on his deathbed by a bishop from the other side. His son Constantius II, sole ruler from 353, backed formulas that avoided homoousios and used councils and exile to enforce them, and by 359 a pair of imperial councils had produced a compromise creed that the Nicene party regarded as a defeat. Jerome later wrote that the whole world groaned and was astonished to find itself Arian.
Example. Athanasius was bishop of Alexandria for 45 years from 328 and spent about 17 of them in exile, expelled five separate times by four different emperors. What does that career show?
That doctrine had become a function of who held power, and that it could not be settled by holding power. Thirty-eight per cent of an episcopate spent in exile is a measure of how completely theological allegiance now determined civil status, since these were not doctrinal punishments imposed by a church but banishments ordered by emperors. Each expulsion was an imperial policy and each return was another.
The second half is the important half. Five expulsions and five returns mean the machinery could remove a bishop and could not replace him, because Athanasius's authority rested on his standing in Alexandria and in the wider church rather than on his tenure of a post. An emperor could take the building; he could not take the following. That is the structural novelty of the fourth century, and it is why the relationship between emperors and bishops develops the way it does. The state was dealing for the first time with an organisation whose leaders it had not appointed and could not simply dismiss.
Now you. How much should Jerome's line about the world waking up Arian be allowed to prove?
Answer
Almost nothing as a measurement and a great deal as testimony to how a defeat felt. Jerome is writing decades later, on the winning side, in a polemical work, and the sentence is a rhetorical flourish about the councils of 359 whose outcome his party had rejected. Neither he nor anybody else had any means of knowing what the world believed.
What it does record accurately is that at one moment the imperial court, most of the eastern episcopate and the official creed were all on the non-Nicene side, and that this was a genuine possibility rather than a passing aberration. The Nicene victory under Theodosius twenty years later was not inevitable and did not feel inevitable at the time. That is worth insisting on, because church history written afterwards by the winners naturally presents the outcome as the recovery of an obvious truth from a temporary confusion, and the surviving sources are almost entirely theirs. When one side writes the record, its account of how close it came to losing is the part most likely to be true.
Julian, the control experiment
In 361 the throne passed to Constantine's nephew Julian, who had been raised Christian, had turned privately to the old gods and philosophy, and now announced it. He is the closest thing this course has to a controlled test of how deep the change had gone, and his reign as sole emperor lasted about twenty months.
Example. Julian restored funding to temples, recalled exiled bishops of every faction in order to let Christians quarrel, and forbade Christians to teach classical literature on the grounds that a man who thinks Homer's gods false should not be paid to expound Homer. He died in Persia in June 363. What did the twenty months establish?
Chiefly that the old religion could not be restored by an emperor's decision, which is the mirror image of the finding about Christianity from the persecutions. Julian's letters record his frustration at what he found: temples without worshippers, priests who had to be instructed in how to behave, and, revealingly, an attempt to organise pagan charity because he could see that the Christians' care of the poor was winning converts and that traditional cult had no equivalent. He was trying to build an institution, and the point about traditional Roman religion, established several lessons ago, is that it had never been one.
The teaching ban is the sharpest of his measures and the most instructive. It shows that Julian understood the real mechanism: not belief but access, since classical education was the gateway to every career in the empire, and excluding Christians from teaching it would in time exclude them from the elite. Even his Christian opponents thought it his cleverest and cruellest act. It was revoked immediately after his death, which is the other finding: a policy that depends entirely on one man lasts as long as he does. On both sides, the fourth century keeps demonstrating that religious change ran deeper than any emperor's power over it.
Now you. In 384 the pagan senator Symmachus petitioned for the restoration of the Altar of Victory to the Senate house, arguing that Rome's greatness had been built under these rites, that an old religion deserves respect, and that so great a mystery cannot be reached by one road alone. Ambrose of Milan answered him and won. Why did that argument fail?
Answer
Because it conceded the ground it was standing on. Symmachus argues from custom, antiquity and the plurality of paths, which is a perfect statement of the traditional Roman position described earlier in this course, where a rite's claim rested on having always been performed. Against an opponent who holds that one account is true and the others are false, an appeal to variety is not an argument but a description of the thing being objected to. Ambrose could simply reply that age is no warrant for error, and did.
There is also a plain political reading, and it should not be crowded out by the elegance of the exchange. Ambrose had access to the court, the emperor's ear, and a threat of ecclesiastical consequences he was willing to use, and the western court by 384 had no interest in a pagan gesture. What is worth noticing is that Symmachus's petition was polite, constitutional and addressed to an emperor as a request. The next section is about a bishop who did not ask.
The bishop as a civic power
While the theology was being fought over, the office of bishop was quietly turning into the most important local institution in the empire.
An earlier lesson showed government delegated to city councils and the notables who staffed them, and the lesson after Diocletian showed those men fleeing an office that had become a hereditary liability. Something had to fill the space, and the bishop did. He controlled substantial revenues, in property given by emperors and by the rich. He ran the distribution of food and money to the poor, which no pagan cult had ever done and which made him a patron on the old Roman model with a far broader clientele. He could hear civil cases between consenting parties, with the state enforcing his judgement, so he was a judge. He interceded with governors for prisoners and taxpayers, ransomed captives, and spoke for his city.
By 400 the bishop of a provincial town was the man a community sent to negotiate, the man who could raise money in an emergency, and the man with a permanent building, a staff and a written record. He was, in the functional sense, what the decurion had been, with the difference that his position was for life and his authority came from outside the imperial hierarchy.
Ambrose and Theodosius
Example. In 390 a riot at Thessalonica killed a Roman commander, and Theodosius ordered a reprisal in which a large crowd was massacred in the circus, thousands according to the sources. Ambrose, bishop of Milan, withdrew from the emperor's presence, wrote to him privately that he could not offer the sacrifice while the emperor came to the church with the blood of an innocent people on his hands, and Theodosius performed public penance before being readmitted to communion. Why is this new?
Because no authority inside the Roman world had ever been able to impose a penalty on an emperor. The Senate could flatter or condemn after death; armies could kill; but no institution could require a reigning emperor to submit to a discipline and have him comply. Ambrose had no troops, no office and no legal power over Theodosius. What he had was control of access to a rite the emperor believed he needed, and the standing to make the exclusion public.
Read carefully, though. Ambrose's letter is respectful, offers a precedent for royal repentance, and gives the emperor a route back, and Theodosius's submission was politically manageable and arguably even useful, since it presented him as pious rather than as a butcher. Both men were skilful and neither was testing a theory of church and state. But the precedent was set and remembered for a thousand years, and the reason it could be set is structural rather than personal: once the emperor's own legitimacy is bound up with a church, the men who run that church have leverage over him that no subject previously had. The empire had acquired a second authority inside itself, and had done so as a side effect of adopting a religion for reasons of state.
Now you. Theodosius died in January 395, leaving Arcadius, aged about eighteen, in the east and Honorius, aged ten, in the west. Historians often call this the division of the empire. Should they?
Answer
Not as it stood. Every element of this arrangement had happened before: the empire had had multiple emperors since Diocletian, with territories, courts and armies of their own, and Theodosius himself had ruled the east while a colleague held the west. There was still one empire, one law and one citizenship, laws issued in one half were published in the other, and consuls were shared. Nobody in 395 announced a partition, and nobody thought one had occurred.
What made this division different is visible only afterwards, and consists of things that were not decided in 395 at all. No emperor ever again ruled both halves in more than name. Both boys were incapable, so power lay with generals and court officials whose interests were regional, and the two courts began competing over revenue, over the Balkan provinces and over which of them was responsible for the Goths. And within fifteen years the western court's military and financial position had deteriorated so far that the two halves' fortunes were plainly separate.
The date is a convenience, then, and worth keeping as one provided the reason is clear. The empire in 395 was administratively divided and politically single. What made the division permanent was the failure of one half, and the next two lessons are about why that half failed.
What a Christian empire had become
By the end of the century the legal position had reversed completely. Theodosius's law of 380 ordered all peoples to hold the faith professed by the bishops of Rome and Alexandria and named everyone else heretics; the council of 381 confirmed the Nicene position; and laws of 391 and 392 prohibited sacrifice, closed temples and forbade even private household cult. Sixty-eight years after Constantine's victory, the religion that had been a capital offence was compulsory and the traditional rites were criminal.
The enforcement was patchier than the laws suggest, and the reversal was not as total as a reading of the code implies. Temples went on functioning in places, rural cult persisted for centuries, the Senate at Rome retained pagan members, and the state had neither the officials nor the appetite to police belief in villages. What the laws did achieve was to remove the traditional cults from public life and from public money, which for a religion that had always been civic was fatal in a way that persecution of individuals would not have been. The old gods did not lose an argument; they lost their funding and their place in the calendar.
The empire that emerges is recognisably Diocletian's state with a church fused into it: the same provinces, the same tax, the same army, plus a parallel hierarchy of bishops with revenues, courts and moral authority over the emperor himself. That is the institution that will still be standing in the west when the imperial government is not. Before that happens, the peoples on the other side of the Danube have to arrive, and the next lesson asks who they actually were and how many of them there were, because the answer is much smaller than the outcome suggests.