The Theonomy of the Cunctos Populos (Edict of Thessalonica) of 380 AD

9 December 2023

By Dr Adi Schlebusch

The Edict of Thessalonica, promulgated by three Roman emperors in AD 380, heralded the inception of European Christendom. Initially, the early Christian Church suffered persecution under the Roman Empire, but this ceased temporarily in the early fourth century. Emperors Constantine the Great and Licinius I, leaders of the empire's western and eastern parts, respectively, issued the Edict of Milan in 313. This edict mandated benevolent treatment of Christians within the empire. However, Constantine’s successors, Constantius II and Julian the Apostate, actually showed a preference for paganism, Arianism, and Judaism over Christianity. 

The Constantinian dynasty concluded in AD 364, succeeded by the Valentinians, who governed the Western Roman Empire until 392 and the East until 378. The dynasty’s first two emperors, Valentinian I and Valens, displayed either neutrality towards Christianity or support for the Arians. Significant changes for Christianity within the Roman Empire began in 367. Gratian, son of Valentinian I, succeeded Valens as emperor. He eschewed participation in the imperial cult and removed several pagan idols from Rome's public spaces. Gratian appointed the Christian bishop Ambrose as his primary advisor and named Theodosius I, his wife's cousin, as Christian co-regent in the East. Under Bishop Ambrose's influence, Gratian and Theodosius recognized the untenability of the prevailing policy of religious pluralism. Gratian's rejection of the imperial cult had created a religious vacuum, effectively disestablishing the empire's public religion. Consequently, along with Valentinian II, the young western co-regent, they promulgated the Edict of Thessalonica, which established Christianity as the official religion of the Roman Empire.

The edict proclaimed: 

We desire that the various nations under our Clemency and Moderation continue to profess the religion delivered to the Romans by the divine Apostle Peter, preserved by faithful tradition, and now professed by Pontiff Damasus and Bishop Peter of Alexandria, a man of apostolic holiness. According to apostolic teaching and Gospel doctrine, we believe in the one deity of the Father, Son, and Holy Spirit, in equal majesty and a holy Trinity. We authorize the adherents of this law to adopt the title of Catholic Christians. However, we regard others as foolish madmen, decreeing they bear the ignominious name of heretics and not presume to call their gatherings churches. They will first face divine condemnation, then punishment from our authority, as Heaven wills.

Also known as Cunctus populos, the first two Latin words of the edict, often translated as “various nations”, could be more accurately rendered as “conjoining nations”. The choice of these words by the Christian Emperors reflects their perception and aspiration for the empire, not as a singular country or nation, but as a commonwealth of Christian nations co-existing peacefully under their rule, thereby eschewing any notions of propositional nationhood. This demonstrates a clear grasp of the Christian principle of the one and the many, rooted in God’s Trinitarian nature, by these eminent emperors.

Calvinist philosopher R.J. Rushdoony observed: 

The reduction of all reality to one in religion is pantheism, presupposing unity as the sole virtue. In contrast, we possess a distinction absent in non-Christian thought: a temporal one-and-many in the created universe, and an eternal One-and-Many in the ontological Trinity.1 

This philosophy underpinned the emperors' governance, differing starkly from the funtionally unitarian aims of Enlightenment-inspired entities such as the United Nations, which disregard God’s created distinctions. European Christendom was marked by a plurality of co-existing authorities exercising decentralized power—dukes, princes, bishops, kings, emperors—all co-reigning for over a millennium. This arrangement persisted until the prevalence of the French Revolution's amalgamationist and universalist objectives, signaling the decline of Western Christendom. It is striking that the Edict of Thessalonica, even in ratifying the Christian religion as official religion of the empire and holding everone accountable to the stndard of Scripture, still recognized and valued the diversity of nations and cultures which constituted early Christendom.

1. RJ Rushdoony, The One and the Many. Thoburn Press: Fairfax, Virginia, 1978, pp. 6, 7,10.