Why was Theodosius successful in ending the Arian Controversy?

In the conventional account of the Arian controversy, the council of Constantinople in the year 381 made an end of that controversy. In reality, the controversy was brought to an end by Emperor Theodosius in the year 380 through the Edict of Thessalonica, in which he outlawed all non-Trinitarian forms of Christianity.

The emperor’s edict was more clearly Trinitarian than the Constantinople Creed of 381. While the Creed identifies the “one God” as the Father, the emperor’s creed identified “the one deity” as the Trinity:

Let us believe in the one deity of the Father, the Son and the Holy Spirit, in equal majesty and in a holy Trinity

Of those who oppose his edict, it said:

They will suffer … the punishment of our authority which … we shall decide to inflict.

On 26 November 380, two days after he had arrived in Constantinople for the first time, Theodosius expelled the Homoian bishop, Demophilus of Constantinople, and appointed Gregory of Nazianzus, one of the Cappadocian Fathers … patriarch of Constantinople. (Theodosius I – Wikipedia – copied 25 Nov 2021)

“In January of the following year (381), another edict forbade the heretics [non-Trinitarians] to settle in the cities” (Boyd, William Kenneth (1905)) 1The Ecclesiastical Edicts of the Theodosian Code. Columbia University Press. p45-46

Therefore, when Theodosius in May 381 summoned a council of bishops at Constantinople, all other views were already outlawed and only people who accepted the Nicene Creed were admitted into this ‘ecumenical’ council:

“Thirty-six Pneumatomachians arrived but were denied admission to the council when they refused to accept the Nicene creed.” (First Council of Constantinople – Wikipedia Retrieved 25 Nov 2021)

Gregory of Nazianzus—the leader of the Nicene party in the city—presided over part of the Council and vehemently opposed any compromise with the Homoiousians (those who believed that the Son’s substance is “similar” to the Father’s). 2Lewis Ayres – Nicaea and its legacy – Oxford University Press

(The homoi-ousians were the ‘Arians’ who were the closest to the Homo-ousians (the supporters of the Nicene Creed). Therefore, since Gregory of Nazianzus vehemently opposed any compromise with the Homoiousians, he also opposed compromise with any of the other views.)

“Several Emperors had attempted to bring an end to the Arian controversy. Constantine, Constans, Constantius … All had failed because … they in fact were not supported by a consensus in the Church at large. Theodosius succeeded because … (he was) backed by a consensus in the Church.” (Hanson Lecture)

The emperors whom Hanson mentions all opposed the homoousian view, exiled homoousian bishops, and appointed bishops that supported their points of view. One must remember that the church became part of the governance structure of the Roman Empire. Boyd wrote:

“The political and social power acquired by bishops … made their election in the days of the later Roman Empire … a matter of public importance. … Consequently, the election of patriarchs was often the occasion of an ecclesiastical synod and the emperors, through their relation to the synods, which they often convened and attended, might exercise a direct influence on elections. Constantine wrote to the council and people of Antioch not to choose Eusebius of Caesarea as bishop of that city. Constantius convened “an assembly of bishops of Arian sentiment” and deposed Paul of Constantinople” (Boyd) 3The Ecclesiastical Edicts of the Theodosian Code page 64

I am not sure that Hanson is right about this “consensus.” If there was consensus, why did he have to exile the homoian bishop of the capital of the empire (Constantinople)? (See Theodosius I – Wikipedia – copied 25 Nov 2021) Furthermore:

Williams & Friell wrote that, by 379, when Theodosius I succeeded Valens, Arianism was widespread in the eastern half of the Empire, while the west had remained steadfastly Nicene. (Williams, Stephen; Friell, Gerard (1994). Theodosius: The Empire at Bay. B.T. Batsford Ltd. ISBN 0-300-06173-0, pp. 46–53)

Church historian Sozomen wrote: Theodosius made known by law his intention of leading all his subjects to the reception of that faith which was professed by Damasus, bishop of ROME, and by Peter, bishop of ALEXANDRIA. (Sozomen’s Church History VII.4)

On the other hand, Hanson stated that in the year 375 there was an incident where the Pope of Rome and the archbishop of Alexandria opposed Basil of Caesarea, the champion of Nicene orthodoxy in the East. (See, Lecture)

So, my question is one for the church historians: Did a consensus exist as Hanson suggested, or was Theodosius successful because he used the might of the sword more effectively than his predecessors? I regard this as an extremely important question because it will determine whether the acceptance of the Trinity doctrine by the church was the decision of:

    • A Roman Emperor, supported by a faction in the church, or by
    • A majority of church officials.


  • 1
    The Ecclesiastical Edicts of the Theodosian Code. Columbia University Press. p45-46
  • 2
    Lewis Ayres – Nicaea and its legacy – Oxford University Press
  • 3
    The Ecclesiastical Edicts of the Theodosian Code page 64

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