In 313 the Roman emperor Constantine, flushed with a military victory against a rival that he attributed to the Christian god, issued an Edict of Toleration in which he promised that “no one whatsoever should be denied freedom to devote himself either to the cult of the Christians or to such religion as he deems best for himself.” It was an important moment. The Romans had been generally tolerant of religious sects but Christians had enraged many by their denigration of traditional gods and this had led to persecution. Now they were brought under the patronage of the state. It was an astonishing turnaround and the church flourished.

Over the next 60 years the principle of toleration was largely honoured and given sophisticated backing. In 364 a pagan court orator, Themistius, argued before a Christian emperor, Jovian, that it was essential to maintain freedom of religion and speech. “A king”, he declared “cannot control his subjects in everything, there are some matters which have escaped compulsion, for example the whole question of virtue and, above all, reverence for the divine.” God had given all “a disposition towards piety … but lets the manner of worship depend on individual inclination.” The health of a society depended on free debate. There was no one road to truth and, he concluded, God actually enjoys being worshipped in a diversity of ways.

Charles Freeman's spread from New Humanist, January/February 2008The benefits of free debate can be seen in the passionate discussions that Christians had in the fourth century over the nature of the Godhead. The crucial question was whether Jesus had always been “one in substance” with the Father, in the formula the bishops had agreed at a council called by Constantine at Nicaea in 325, or was a later creation and thus subordinate to him, as had been traditionally believed by earlier Christians. For anyone with training in traditional Greek philosophy it must have been obvious that here was an issue that could never be resolved. Many bishops recognised this. As one group of them observed in 357, the issue “is beyond man’s knowledge nor can anyone declare the birth of the Son … for it is clear that only the Father knows how he begot the Son and his Son how he was begotten by the Father.” This did nothing to deter intense argument. Both sides had impressive contributors, many of whom were well versed in Greek philosophy, and there was a staggering array of philosophical concepts involved, including the meanings in this rarified context of “existence”, “identical”, “substance”, “begetting”, “nature” and “mind”. Today a great deal of theology seems to be concerned with finding better arguments for what is already defined as orthodoxy. In the heady days of the mid-fourth century there was as yet no orthodoxy and the quality of debate was much less restrained as a result.

It was political developments that brought all this to an end. In 378 the Roman legions had suffered a devastating defeat by Gothic forces at Adrianople in the Balkans. The emperor Valens died leading his troops. In the ensuing panic the remaining emperor, Gratian, appointed a tough Spanish soldier, Theodosius, as emperor over the Greek-speaking eastern half of the empire. Theodosius was desperate to restore order before the empire fragmented under the pressure of the “barbarians”. One way of doing this, he believed, was to strengthen the empire under a single religious formula. A supporter of the Nicene formula himself, Theodosius dramatically broke with the policy of toleration by announcing that henceforth only Nicene bishops could have churches within cities, and that other Christians, now dubbed “demented and insane heretics”, would have to give up their churches and be subject both to imperial and divine vengeance. When he entered his capital, Constantinople, for the first time in 380, Theodosius enforced his policy and the “subordinationist” bishop of the city was immediately dismissed.

To give some credibility to his actions, Theodosius summoned a council of bishops who were already committed to his own faith to Constantinople to endorse it. The council was a shambles. The first presiding bishop, Meletius of Antioch, died. The second, the new bishop of Constantinople, the intellectual Gregory of Nazianzus, proved hopelessly inadequate and was soon forced to resign. Recourse had to be made to a respected pagan senator, Nectarius, who was quickly baptized so that he could preside and restore order. Although the Council apparently passed a new Nicene creed, it proved impossible to publish it in the hostile capital and the first historical reference to it comes only some seventy years later.

Soon after 381 the emperor began enforcing new laws against dissidents. The Manicheans, followers of the Persian prophet Mani, were the first to be banned. There followed a list of Christian heresies that expanded inexorably after no sustainable dividing lines between acceptable and unacceptable religious belief could be established. One law of 428 listed twenty specific heresies. When a new theological issue, the problem of relating Jesus’s humanity to his divinity, arose in the fifth century, there were bitter and intractable debates when the borders between orthodox and heretical proved impossible to define. Again a single formula, the Chalcedonian (which accepted that Christ had two natures, human and divine), was imposed by the emperors with a fresh array of legislation against newly defined heretics.

Once the principle that the state should control religious belief had been established, the laws extended far beyond Christianity. Some of Theodosius’s more fanatical officials instigated the burning down of pagan shrines and in the 390s all forms of pagan belief were condemned. The Olympic Games, a festival in honour of Zeus, were held for the last time in 393. When Theodosius, under pressure from Ambrose, the formidable bishop of Milan, condoned the burning down of a synagogue by a Christian mob, the exclusion of Jews from all official posts followed.

The only precedent for the breadth of the laws against religious belief comes from the 14th century BC, when the Egyptian pharaoh Akhenaten decreed that the sun god Aten should be the only deity. His campaign collapsed at his death, but Theodosius’s endured. When the empire fell in the west, the popes announced that the Nicene Trinity was an article of faith endorsed by the Council of Constantinople. This rewriting saw the crucial role of Theodosius suppressed. In works on church history today, the Nicene solution is said to be the only theologically coherent solution to the problem and the subordinationist view, which has far more scriptural support than the Nicene, remains derided. Few Christians ever realise that their freedom to discuss their own religion was, in effect, destroyed by a Roman emperor.

If Theodosius had maintained his predecessors’ policy of toleration, the debate would surely have fizzled out as one beyond resolution, as the wise bishops of 357 recognized. The history of Europe would have been very different if Themistius’s formula that God enjoys being worshipped in a diversity of ways had passed into the western tradition after the fall of the empire. The year AD 381 thus deserves to be seen as one of the defining moments in the history of European thought, and the history of Christianity should be rewritten to acknowledge it.