Peter Heather, in his The Fall of the Roman Empire, describes the way in which the Christian Church came to enjoy its role as a public institution. He notes, “After Constantine’s public adoption of Christianity, the long-standing claims about the relation of the state to the deity were quickly, and surprisingly easily, reworked” (123). Heather is going to refute many of the claims of Edward Gibbon, those that assert Christianity had a violent effect upon the empire. This will also contradict the lesser known claims, though important to my ecclesiastical community, of Rushdoony in his The Foundations of Social Order. (It really is a terrible book. Perhaps one day I will take the time to refute some of its claims myself, but for now I will simply say that it could hardly be farther from the actual way history unfolded.)
Heather describes the instillation of Christianity quite succinctly, and I will be happy to simply quote some of his best lines. Heather writes:
At the top end of Roman society, the adoption of Christianity thus made no difference to the age-old contention that the Empire was God’s vehicle in the world…
This ideological vision implied, of course, that the emperor, as God’s chosen representative on earth, should wield great religious authority within Christianity. As early as the 310s, within a year of the declaration of his new Christian allegiance, bishops from North Africa appealed to Constantine to settle a dispute that was raging among them. This established a pattern for the rest of the century: emperors were now intimately involved in both the settlement of Church disputes and the much more mundane business of the new religion’s administration. To settle disputes, emperors called councils, giving bishops the right to use the privileged travel system, the cursus publicus, in order to attend. Even more impressively, emperors helped set the agendas to be discussed, their officials orchestrated the proceedings, and state machinery was used to enforce the decisions reached. More generally, they made religious law for the Church– Book 16 of the Theodosian Code is entirely concerned with such matters– and influenced appointments to top ecclesiastical positions.
The Christian Church hierarchy also came to mirror the Empire’s administrative and social structures. Episcopal dioceses reflected the boundaries of city territories (some even preserve them to this day, long after they have lost all other meaning). Further up the sale, the bishops of provincial capitals were turned into metropolitan archbishops, enjoying powers of intervention in the new, subordinate sees. Under Constantine’s Christian successors, the previously obscure Bishop of Constantinople was elevated into a Patriarch on a par with the Bishop of Rome– because Constantinople was the ‘new Rome.’ Very quickly, too, local Christian communities lost the power to elect their own bishops. From the 370s onwards, bishops were increasingly drawn from the landowning classes, and controlled episcopal successions by discussions among themselves. With the Church now so much a part of the state– bishops had even been given administrative roles within it, such as running small-claims courts– to become a Christian bishop was not to drop out of public life but to find a new avenue into it. If the Christianization of Roman society is a massively important topic, an equally important, and somewhat less studied one, is the Romanization of Christianity. The adoption of the new religion was no one-way street, but a process of mutual adaptation that reinforced the ideological claims of emperor and state.
This imperial character of the early church cannot be overestimated. This is how we came to have “ecumenical councils.” This is why some councils won out over others. This would be why there developed “Eastern” and “Western” branches of the Church, and this civil character of ecclesiastical organization is also why there could come to be “Byzantine” Christianity or “Frankish” catholicism.
This is also why the Protestant Reformation could happen. Different in so many ways, Martin Luther and Henry VIII both understood the role of princes in church polity.