Constantine founded Christendom—or so we are told. Thus, we tend to imagine a great deal of continuity between him and, say, medieval Catholicism or the magisterial Reformation in how they supposed Christianity ought to relate to the public sphere. I think this is misleading on a few fronts. In the first place, Constantine did not make Christianity the empire’s official religion. That change cannot really be said to have taken place until the Theodosian dynasty. In 380, Theodosius I and his co-emperors declared their will that all their subjects ascribe to the catholic faith (defined by the standard of faith as per the bishops of Rome and Alexandria).^[1] In a different example, it was only about a century after Constantine that emperors such as Honorius, Valentinian III, and Theodosius II banned Jews from serving in most governmental positions.^[2]

While he certainly patronized Christianity and intervened in the ecclesiastical affairs of his day, Constantine largely left alone Christian sectarians and most pagans (with some interesting exceptions to be discussed another time). As I’ve discussed before, some prominent scholars have begun to see toleration as one of Constantine’s political virtues, and I’m increasingly persuaded there’s something to that.

A fascinating case study here is Manichaeism. About 13 years before Constantine’s alleged epiphany at the Milvian Bridge, the emperor Diocletian published a strident decree ordering that Manicheans and their nefarious books be burned.^[3] Of course, Diocletian was also keen to persecute mainstream Christians as part of his larger agenda to promote old timey Roman values (and I think in the Tetrarchy there are some historical warnings against reactionary traditionalism in our own politics and culture, but that too is for another time). In Diocletian’s eyes, the Manicheans were not only weird (just like Christians) but they were also foreign, a profile that Roman officials tended to find especially spooky. Fast forward to the year 435: Theodosius II not only restricts the assembly of various Christian sectarians, he singles out the Manicheans as the very worst of the worst, banning them from the cities.^[4]

Notably, this was not Constantine’s approach nor that of his immediate successors. Remember, in 311–313, Constantine and his rival/co-emperors had granted broad toleration of religion to everyone in the empire, including the widely despised Manicheans. In general, this policy of toleration seems to have held for most of the fourth century, despite the fact that the Manichean dogmas would probably have been considered blasphemous by many Christians.^[5]

I think this interlude of toleration is interesting for two reasons. First, it reframes that blunt story of continuity between Constantine and all subsequent Christian polities. Apparently, it is possible to have highly successful Christian prince or “magistrate” who also promotes religious freedom. Here, perhaps Constantine and his advisers discerned that it was better to do away with state persecution, insofar as such persecution had once harmed many catholic Christians and could do so again. Lactantius, a member of Constantine’s court, certainly made such a case, arguing that religious belief could not and should not be compelled.^[6] To repeat, I think this all rather explodes certain notions about what a Christian politics can and must do. That said, it bears stressing that neither Constantine nor any other emperor was a religious “libertarian” holding to some nascent version of our current jurisprudence on the First Amendment. Even so, it’s probably fair to say Constantine hardly anticipated the Spanish Inquisition.

Second, why did toleration fall out of favor in the Theodosian era? One answer might be that “normal” Roman instincts about religious consensus and regulation of nonconformity simply reasserted themselves: there are quite a few similarities between Roman perceptions of Manicheans in the later fourth century, catholic Christians in the second, and Bacchic cultists way back in the Republican era. A related and perhaps commonsensical factor might be demographics. Taking one famous sociological estimation as a rough-and-ready model, Christians would have only comprised about 18% of the Roman population in 315; by 350, this jumps to 56%, which one assumes only climbed in the subsequent decades.^[7] Where religious toleration might have been a smart, advantageous policy for Christians in Constantine’s day (d. 337) just coming out of an era of harsh persecution, in the later 300s into the 400s, it would have seemed like a carve out for suspicious religious minorities.

In the dynamics of that change, I think we probably have another political lesson for today’s Christians as they face demographic decline (hint: not effecting Christian nationalism or its penumbras), but I leave that for the reader to discern.

1. See Codex Theodosianus 16.2. ↑
2. Amnon Linder, “The Legal Status of Jews in the Byzantine Empire,” in Jews in Byzantium: Dialectics of Minority and Majority Cultures, ed. Robert Bonfil et al., Jerusalem Studies in Religion and Culture, vol. 14 (Leiden ; Boston: Brill, 2012), 157ff. ↑
3. Collatio 15.3.6: iubemus namque auctores quidem ac principes una cum abominandis scripturis eorum seueriori poenae subici, ita ut flammeis ignibus exurantur. See the whole decree in M. Hyamson, ed., Mosaicarum et Romanarum Legum Collatio., trans. M. Hyamson (London; New York; Toronto; Melbourne; Bombay: Henry Frowde; Oxford University Press, 1913), 131–3. ↑
4. See Codex Theodosianus 16.65.2. Valentinian I had also restricted Manichean gatherings earlier in 372, but there the concern seems to be with witchcraft and not so much the beliefs per se. It was probably not until Theodosius I’s comprehensive legislation of the early 380s that the sect was persecuted again in earnest. ↑
5. See discussion in Samuel N. C. Lieu, Manichaeism in the Later Roman Empire and Medieval China: A Historical Survey (Manchester: Manchester University Press, 1985), 95–7, 110–11. ↑
6. See, for instance, his Divine Institutes 5.14 and 5.20. ↑
7. Rodney Stark, The Rise of Christianity: How the Obscure, Marginal Jesus Movement Became the Dominant Religious Force in the Western World in a Few Centuries, unknown edition (San Francisco: Harper, 1997), 7. It should be underscored that Stark himself thought these estimates were highly conjectural. ↑