Historical Development of the Trinity Doctrine – Fifth Century Arianism

This is an article in the series on the historical development of the Trinity doctrine. The current article considers the Fifth Century but also provides an overview of the events of the preceding centuries.


Pre-Nicene Church Fathers


The church fathers of the first 300 years were not Trinitarians. The Trinity doctrine was only developed in the fourth and fifth centuries. For the pre-Nicene church fathers, in general, the Father was “the only true god.” They had an extremely high view of Christ, for example, that He was “born of the very substance of the Father” “before time began” but they nevertheless regarded the Son as subordinate to the Father, who is “the Head of Christ.” For example, see Irenaeus.

Nicene Creed


After Emperor Constantine legalized Christianity in the year 313, he has an important role in the formulation of the Nicene Creed of 325 in that he allowed a small minority to determine the final form of that creed. That creed elevates the Son to “true god from true god.”

(I use the word “god” because the ancient languages did not distinguish between upper- and lower-case letters. Consequently, the ancient languages did not have a word equivalent to the modern word “God.” In Greek, they used the word theos, which is a general word used for all gods.) 

Fifty year Arian period

However, after the Council of Nicaea in the year 325, the Arian controversy continued. That council rejected Arius’ views, but it caused a second controversy; not between Arius and the rest, but between the followers of Origen and the minority party that added the word homoousios with Constantine’s blessing. (See – Eusebius of Caesarea)

Soon after 325, Emperor Constantine became convinced that the Nicene Creed is not Biblical. During the next 50 years, all Christian emperors rejected the Nicene Creed. Consequently, the church also rejected the Nicene Creed. (Religious freedom was not part of Roman culture.) During the next 50 years, there was a range of alternative theories about the relationship between God and His Son. Trinitarians often cluster them all under the title Arianism but most of them were very different from what Arius taught.

Several alternative creeds were accepted by the church during those 50 years. While the Nicene Creed sought to emphasize equality between the Father and Son, in all of the creeds formulated in the 50 years after Nicaea, the Son was regarded as subordinate to the Father. See, for example, the Long Lines Creed.

During that fifty-year period, the church converted many Germanic peoples to Christianity and taught them a non-Nicene Christology. Also at this time, Germanic people began to migrate into the Roman Empire in large numbers.

However, in the year 380, Theodosius became emperor. Being a zealous supporter of Nicene Christianity, he immediately outlawed all other forms of Christianity. He persecution nwas so effectively that non-Nicene Christology disappeared among the elite in the empire. However, the Germanic peoples (called ‘barbarians’ by the Romans) remained Arian.

Barbarian domination of the West

After Theodosius died in 395, the Germanic immigrants, due to their numbers and military prowess, became a dominant force in the Roman Empire. They tolerated figurehead Western Roman Emperors until 476. However, in that year a Germanic chieftain deposed the last Western Roman Emperor. They then divided the territory of the western provinces between the Germanic tribes. However, these tribes continued to function as part of the Roman Empire. Since these Germanic tribes were non-Nicene, the Western Roman Empire was once again non-Nicenedominated.

The Roman Church in the Fifth Century

The Roman Church survived throughout this turmoil. One reason is that the Germanic tribes wished to remain part of the Roman Empire and tolerated the Roman Church because it was an official part of the Roman system of government. For that reason also, the Roman Church actually grew in strength.

One consequence of the growing strength of the Church in Rome was that the Germanic peoples converted to the Nicene Church, rather than to Arianism. The Franks were the first to convert. The other nations converted to Nicene Christianity over the subsequent centuries.


The purpose of this article series is to show that the religious preferences of the Roman Emperors determined the Christology of the church. The fact that the church today is dominated by the Trinity doctrine is the direct result of decisions taken by Roman Emperors. The current article refers to the roles which Constantine and Theodosius played. The next article discusses Justinian’s wars on the Arians.


Church Fathers – First 300 Years

The Church Fathers of the first 300 years were not Trinitarians. For them, the Father alone was the “Lord God Almighty,” “the only true god, the unbegotten and unapproachable” and the “Lord of the universe.”

But they also had an extremely high view of Christ: They wrote that He was “born of the very substance of the Father” “before time began.” “Every knee should bow” before Christ Jesus. But that is not because Jesus is the Almighty, but because it is “the will of the invisible Father.” In other words, in their view, the Son is subordinate to the Father, who is the only true ‘god’. Justin Martyr explicitly put Jesus “in the second place” next to God. Irenaeus, quoting the New Testament, refers to the Father as “the Head of Christ.” Polycarp, also quoting the Bible, identified the Father as Jesus’ God (e.g. Rev. 3:12).

Nicene Creed (325)

After Christianity was legalized in 313, emperor Constantine played a huge role in the formulation of the Nicene Creed of 325. While the Bible and the early fathers described the Father as “the only true god,” the Nicene Creed elevated the Son as Homoousios (same substance) with the Father and as “true god from true god.” This elevates the Son to near equality with the Father. The article Nicene Creed discusses whether that creed declares the Son to be fully EQUAL to the Father.

The words “God” and “god”

The reader might be surprised by the references in this article to “god” rather than to “God.” The reason is that ancient languages did not distinguish between upper- and lower-case letters. Consequently, the Bible writers and these early fathers did not have a word that is exactly equal to the modern word “God,” which we use today as a name for one specific Being; the uncaused Cause of all things. The ancient word which they used (theos in Greek) had a more general meaning and is equivalent to the modern word “god.” They used that same word for the Greek gods.

These early writers (Ignatius, Irenaeus, etc.), therefore, literally referred to the Father as “the only true god,” but to Jesus as “our god. To translate theos as “God,” with a capital “G,” is an interpretation. Translators today, generally, assume the Trinity doctrine in which Jesus Christ is equal with the Father. Both are regarded as the uncaused Cause of all things. Such translators translate theos, when it describes Jesus, also as “God.” 

It is important to know that that is an application of the Trinity doctrine and does not necessarily reflect the intention of the early writers.

As shown above, the earliest church fathers had an extremely high view of Christ but did not regard Christ as equal to the Father. For that reason, it may be preferable to use the word “god” rather than “God.” That might reflect the intentions of these ancient writers better. For example, the phrase “true God” is a tautology, for there is only one true God. But “true god” is a logical phrase. See the article Jesus is our God for a further discussion of this crucial principle.

Fifty-years Arian Period (330-380)

The Council of Nicaea did not end the Arian controversy. The bishops went on teaching as they had before. Within a few years after Nicaea, Church leaders convinced emperor Constantine that the Nicene Creed was not Biblical. During the 50 years after Nicaea, the emperors were Arian. For that reason, Arianism dominated the church in that period (See Fourth Century Arian Period.). 

Religious freedom was not part of the culture of the Roman Empire. Just like Constantine exiled all church leaders who did not accept the Nicene Creed, the emperors after Constantine viciously persecuted the church leaders who taught the Nicene Creed. 

Many alternative creeds were formulated during that 50-year Arian period, for example, the Long Lines Creed.

During those fifty years, the Gothic convert and Arian bishop Ulfilas went as a missionary to the Gothic tribes across the Danube. Ulfilas translated the Bible in Gothic and had success in converting the Goths to the Arian form of Christianity. The conversion of Goths led to a widespread diffusion of Arian Christianity in the years 340 to 350 among other Germanic peoples as well, such as the Visigoths, the Vandals, the Lombards, Svevi, and Burgundians. (See the Wikipedia page on Arianism and the Britannica pages for Goth and Ulfilas.)

More or less at this time, the Germanic tribes began to migrate in large numbers into the Roman Empire. (See Migration Period.) Rome referred to them as “barbarians,” but they were the people that occupy most of Europe today.

Death of Arianism (380)

In 380, Theodosius became emperor. He was a zealous Nicene Christian and immediately outlawed Arianism. He so effectively persecuted Arianism that it disappeared among the elite in the empire. However, not being subject to the Roman emperor, the Germanic tribes remained Arian.

Barbarian Control of the Western Empire

As discussed in The Fall of Rome, more and more Germanic immigrants were recruited into the Roman army. The Imperial forces became dependent on Germanic soldiers. They were also appointed in top positions in the military of the Western Roman Empire. Since Roman generals always were very influential in the Roman Empire, this put the ‘barbarians’ in a very strong position. 

Theodosius was the last Roman emperor to rule the entire Empire. Soon after his death in 395 Germanic people were, in reality, in charge of the Western Roman Empire. But the Graeco-Roman population still treated them as second-class citizens. Therefore, to obtain equal rights and permanent residency in the empire, the Germanic people revolted against the severe conditions of their tenure in the Roman Empire. They sacked Rome in 410 and again in 455. (See Fall of the Roman Empire.)

Although they dominated the Western Empire already from the beginning of the 400s (the fifth century), they tolerated figurehead Western Roman Emperors until 476. In that year Odoacer—an Arian Germanic chieftain—deposed the last Western Roman Empire. He soon conquered the whole of Italy. During that time, the territory of the Western Empire was divided between the Germanic tribes, particularly the Goths and Vandals. However, to some extent, they still functioned as part of the Roman Empire. In name at least, they were subject to the emperor in Constantinople. For these reasons, historians today prefer to refer to the Transformation of the Western Roman Empire; rather than to its Fall. It was a slow process over decades and even centuries during which the Germanic people wrestled control of the Western Empire from the Romans. 

Theodosius had made an end of Arianism among the Roman people in 380, but now, through the Germanic domination of the Western Roman Empire, it was once again Arian dominated.

The Roman Church in the Fifth Century

The Roman Church could have perished.

The Roman Church survived throughout this period. There are at least two reasons why we might have expected the Church in Rome to perish with the demise of the Western Empire:

Part of the Roman Government 


Firstly, the Church in Rome was part of the government of the Roman Empire.

After emperor Constantine I legalized Christianity in 313 AD, the church became closely married to political powers of the times. It became very different from what we know today as a church: It rather functioned as a government department. The emperor was the real head of the church. He appointed bishops and they were accountable to him. The emperor also had the final say with respect to controversies in the church, such as concerning Christology. For example:

Emperor Constantine had a huge role in the decisions of the Council of Nicaea. He called the council, presided over it, guided the discussions, proposed and enforced the important word Homoousios and exiled all bishops that did not agree.

When Theodosius I became emperor in 380, the imperial capital was solidly Arian. But he immediately outlawed all other forms of Christianity, exiled Arian bishops, and banned Arians from the Council of 381. The 381 Council was simply a formality. (See Death of Arianism.)

Christianity, consequently, became wealthy and the religion of any ambitious civil official.

Secondly, the Church in Rome advocated Nicene Christology, while the Germanic peoples were Arians. 

Since Nicaea – in the year 325 – because the Church functioned as a department of government, these Nicene and Arian Christians often exiled and persecuted one another. Constantine’s successors—the emperors Constantius and Valens actively encouraged the church to reverse the Nicene Creed and they exiled bishops adhering to the Nicene Creed, crushing the Nicene party (see Fourth Century Arian Period). Theodosius, on the other hand, was a Nicene Christian and acted mercilessly against ‘heretics’. He was responsible for the first official executions of Christian ‘heretics’. [Jones 1964, p. 164]


Despite these factors, the new Germanic Arian rulers in the fifth century in the Western Empire allowed the Church in Rome to continue unhindered. Arianism and the Nicene church of the Roman people existed side by side. The Jewish Encyclopaedia describes the situation:

“Most Germanic peoples—such as the eastern and western Goths, as also the Franks, the Lombards, the Suevi, and the Vandals—were baptized into Arian Christianity. These tribes settled in widely spread districts of the old Roman empire. A large number of Jews, already resident in those lands, fell under Arian domination. In contrast with the domination of the orthodox church, the Arian was distinguished by a wise tolerance and a mild treatment of the population of other faiths. This conduct was traceable to some degree to certain points of agreement between the Arian doctrine and Judaism. The very insistence upon the more subordinate relationship of the Son to the God-father is much nearer to the Jewish doctrine of the Messiah than to the conception of the full divinity of the Son, as enunciated at Nicaea.”
(Kohler, Kaufmann; Krauss, Samuel. “ARIANISM”. Jewish Encyclopedia. Kopelman Foundation.)

The Wikipedia – State Church of the Roman Empire states that the tolerance of the Arian Germanic tribes towards other religions resulted in entirely separate Arian and Nicene (catholic) systems of churches and bishops in the previous Western Empire. 

Although the Arian Germanic tribes were generally tolerant towards Nicene Christians, the Vandal regime in North Africa tried to force their Arian beliefs on their North African Nicene subjects, exiling Nicene clergy, dissolving monasteries, and exercising heavy pressure on non-conforming Nicene Christians. This matter will become important when we read of emperor Justinian’s efforts in the sixth century to regain control of the Western Empire, for the first ‘barbarian’ nation which he attacked was the Vandals.


The Arian nations allowed the Roman (Nicene) Church to co-exist unhindered for at least the following reasons:

The Germanic people, after they took control of the Western Empire, intended to remain part of the Roman Empire and the Roman Church was part of the Roman system of government; accountable to the emperor. The Germanic people voluntary—in name at least—subjected themselves to the Roman Emperor, who reigned from the east. 

Religious persecution was part of the Roman culture. Roman emperors always used religion to strengthen the unity of their vast empire and persecuted religions that threaten unity. But, according to Daniel, the Roman Empire “devoured and crushed and trampled” (Dan. 7:7). Perhaps the barbarians were not as barbaric as the Romans.


Actually, instead of perishing, the Church in Rome grew in strength after the ‘barbarians’ wrestled control of the western provinces from the original Graeco-Roman population (Britannica). The reasons include the following:

The Church had a strong, centralized organization: The pope in Rome is the head of the Church. All clergy, including bishops and priests, fell under his authority. Bishops supervised priests; the lowest ranking members of the clergy. For most people, local priests served as the main contact with the Church.

At the same time, after the fall of the Western Roman Empire, there was no single state or government that united all people who lived on the European continent. The transformation of the Western Roman Empire in the fifth century was a time of great political chaos and warfare and the well-organized church became the only stabilizing force. As secular governments came and went, the Papacy remained. The church was a stable force during an era of constant warfare and political turmoil.

The Church also bonded people together. It gave a sense of communal identity. At the local level, the village church was a unifying force in the lives of most people. It served as a religious and social center. Religious holidays, especially Christmas and Easter, were occasions for festive celebrations.


One consequence of the strength and influence of the Church in Rome was that ‘barbarian’ nations converted to the Nicene Church, rather than to Arianism:

The Franks and the Anglo-Saxons also were Germanic peoples but never were Arians. They entered the Western Roman Empire as Pagans.

In 496, Clovis, king of the Franks, converted to Nicene Christianity—as opposed to the Arianism of most other Germanic tribes. Consequently, sometime between 496 and 508, Clovis I forcibly converted the Franks to Christianity. (So much for religious freedom!) This led to widespread conversion among the Frankish peoples across what is now modern-day France, Belgium, and Germany. Three centuries later, it led to Charlemagne‘s alliance with the Bishop of Rome. This was the first of the Germanic peoples to convert to Nicene Christianity.

Æthelberht of Kent did the same for the Anglo-Saxons (see also Christianity in Gaul and Christianisation of Anglo-Saxon England)

Visigothic Spain was Arian until 589. 

The Lombards were Arians until the 7th century.


The first main conclusion from this article is that the religious preferences of the Roman Emperors determined the church’s Christology. Emperor Constantine had a huge role in the formulation of the Nicene Creed. During the next 50 years, the emperors Constantius and Valens enforced Arianism. In 380, Theodosius—a zealous Nicene Christian—became emperor and immediately outlawed Arianism. In the fifth century, Germanic immigrants dominated the Western Empire. Since they were Arians, the West was Arian once again. But, as the next article will show, in the sixth century, emperor Justinian gave Arianism a death wound and it died during the subsequent Byzantine Papacy. The fact that the church today is dominated by the Trinity doctrine is the direct result of decisions taken by Roman Emperors.

The second main purpose of this article is to explain how the Papacy rose to dominance. This topic will be developed further by subsequent articles.


Christology of the persecuted church (First 300 years)
 – Introduction
 – Polycarp
 – Justin Martyr – Current Article
 – Ignatius of Antioch
 – Irenaeus
 – Tertullian – work in progress

 – Origen – work in progress
 – Jesus is our god.
Fourth Century (State Church)
 – Council of Nicaea – A.D. 325 
 – The Nicene Creed Interpreted 
 – Fourth Century Arian Period 

 – What did Arians believe in the fourth century?
 – Long Lines Creed – one of the creeds during the Arian period
 – Death of Arianism – Emperor Theodosius
Fifth Century
 – Fall of the Western Roman Empire
 – Why the Roman Empire fell 
 – The Fall of Rome proves Daniel as a true prophecy.
 – Roman Church grew in strength
Sixth Century
Justinian and the Byzantine Papacy eliminated Arianism.
Middle Ages

 – The massacres of the Waldensians

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