By Bart D. Ehrman, The University of North Carolina, Chapel Hill
There is God, the father, and Jesus Christ, who himself is divine. And yet, for the Christians, who were monotheists, how could both the Father and the Son be divine if there’s only one God? This had been a long-standing issue. A popular Egyptian teacher, Arius, wrote up his view and declared: “There could be only one ultimate God. Only one who is almighty, if two are all almighty then neither one of them is all-mighty.”
The Donatist Controversy
During his reign, from early on, Constantine became personally involved in the practical and theological disputes of the Christian Church. It started with the Donatist controversy.
Constantine got dragged in when the bishop of Carthage, in North Africa, ordained by a bishop who later became a traditore was sought to be replaced by Donatus and his many followers. This was an argument over sacramental theology that had serious real-life implications and thus, Constantine felt like he needed to interfere.
The Council of Arle
Constantine originally thought the solution was simple, he would appoint an expert to make the decision. So, he turned the case over to the bishop of Rome.
The bishop of Rome decided against the Donatist and declared that the bishop of Carthage was legitimate. The Donatist refused to accept the ruling and appealed again to the emperor. This time, Constantine took it into his own hands and called for an entire council of bishops to come together and debate. The council took place in the city of Arle, in 314 CE.
Constantine’s Disdain for Rigorists
The Council of Arle came to the same decision the bishop of Rome had, ruling against the hardliner Donatist. The bishop of Carthage was legitimate, even if he had been ordained by a traditore, but the Donatus again refused to accept the ruling and asked Constantine himself to intervene. By this time he was fed up with them and it appears that he frankly didn’t care too much one way or the other.
And yet, throughout his long career, Constantine showed disdain for rigorists, unwilling to compromise. So, he, too, decided against the Donatists. That didn’t end the controversy, it continued to rage on and was still a very hot debate in the days of the great 5th century theologian, Augustine.
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The Arian Controversy
There was only so much an emperor could do to influence the theological views of committed religionists. That became clearer in an even better-known ecclesiastical dispute, that Constantine found himself embroiled in a decade later, the Arian controversy.
The council of bishops that Constantine called to resolve it, was known as the Council of Nicaea. Contrary to what is popularly said, the Council of Nicaea did not decide which books would be in the New Testament. This was not a matter they discussed. And they certainly did not decide whether Jesus should be considered the son of God. Everyone at the council firmly believed he was the son of God, as virtually all Christians had for nearly three centuries.
The issue, instead, involved the question of what it might mean to say, he was the son of God? And about that there was a huge controversy. As it turns out, Constantine himself thought and said the debate was somewhat ridiculous and exceedingly trivial.
The controversy began in the large and influential church in Alexandria, Egypt. Initially, it was a disagreement between a bishop, who was coincidentally named Alexander, and one of his clergy underlings, a popular teacher named, Arius, hence the name the Arian controversy.
Christ, the Son of God

Alexander had asked his subordinate clergy to explain how Christ could be the son of God, in some sense actually divine, if the Father alone was God. Christians had long considered Christ the son of God, who had been involved with creating the world, and then later became a human, as expressed most famously in the New Testament, in the Gospel of John 1.
For Arius, Christ himself did pre-exist his birth and was involved with the creation of the world and he was divine. That was because he was brought into existence by God, the Father who begat his Son in eternity past. Through him, he then created the world. Thus, Christ then was not eternal with the Father or equal with him, he was a subordinate divine being who had come into existence. At one time, he did not exist and then later, he did.
For Arius, only God, the father, was truly eternal and all powerful. Christ was divine and powerful, but the glory of the Father exceeded the glory of Christ by an infinite degree, just as Christ’s glory exceeds a human’s by an infinite degree.
Christ, Co-eternal with the Father
And yet, Arius’s bishop, Alexander, could not disagree more. In his view, Christ had always existed and was not subordinate to God, the Father, but in fact was fully equal with the Father, in every way.
There’s a certain logical sense to this if we apply certain forms of philosophical thought to it. A being who is perfect can never change. If God, the Father, is perfect, he cannot change, but that means he cannot become a father because that would mean he changed his status, making him either more or less perfect.
Thus, that means that God always had to be the Father, which means that Christ, his son had always been his son. So, he had always existed. Christ then, in Alexander’s view, was co-eternal with the father. He was not simply like God, the Father, but had the very same substance as the Father.
Common Questions about the Arian Controversy
The Council of Arle came to the same decision the bishop of Rome had ruling against the hardliner Donatist.
For Arius, only God, the father, was truly eternal and all powerful. Christ was divine and powerful, but the glory of the Father exceeded the glory of Christ by an infinite degree
For Alexander could, Christ had always existed and was not subordinate to God, the Father, but in fact was fully equal with the Father, in every way.