The great size and diversity of the Roman Empire, and the separate military threats it faced across the Rhine-Danube frontier in the West and the Euphrates in the East, made its governance unwieldy. Constantine's solution was to establish a new imperial capital at the ancient city of Byzantium on the Bosphorus, the strategic meeting point of Europe and Asia. Beautifying the city and enlarging the circuit of its walls, in 330 he dedicated Nova Roma, as he called Byzantium, to Jesus Christ-though it quickly became known as the city of Constantine, Constantinople.
In 395 a more radical step was taken, and the Roman Empire was formally divided into a western empire ruled from Rome and an eastern empire ruled from Constantinople. Greek culture and language increasingly reasserted themselves in the East Roman Empire, which, taken together with its Christian foundations, has led modern-day historians to give it a different name, the Byzantine Empire. But long after Rome fell to the barbarians in 476, and throughout its struggle in the Middle
Ages against Islam, and indeed right up to the last when Constantinople fell to the Ottoman Turks in 1453, the emperors and their subjects in the East called themselves Romans and spoke of their empire as the Roman Empire.
It is to Constantine, too, that the Christian empires owed their sense of orthodoxy. For no sooner was Christianity tolerated than it was threatened by doctrinal splits. The arguments were not over whether Jesus was divine-his divinity was almost universally agreed. Rather they concerned the nature of that divinity. And during Constantine's reign, the first great heresy emerged-Arianism, so named after a priest of Alexandria.
Arius argued that as Jesus was the Son of God, then surely he was younger than God: an appealing notion that brought Jesus closer to mankind and emphasised his human nature. But another Alexandrian, a bishop called Athanasius, saw a danger. If Jesus was younger than God, so there must have been a time when Jesus was not. This challenged the unity of the godhead-the Father, the Son and the Holy Spirit-and opened the way to regarding the nature of Jesus as being not of the same substance as God's. Indeed in time Jesus might be seen merely as a good man, as Unitarians and Muslims see him today, while God would become less accessible and more remote. The counter-argument of Athanasius was that no distinction could be made between Christ and God, for they were of the same substance.
Seeing the Christians within his empire divided between the arguments of Arius and Athanasius, in 325 Constantine summoned the First General Council of the Church at Nicaea, not far from his future capital of Nova Roma. Two hundred and twenty bishops were in attendance, from Egypt and Syria in the East to Italy and Spain in the West. The divine nature of Jesus Christ was argued from both the Arian and Athanasian points of view, and when the bishops balloted on the issue, it was decided in favour of Athanasius by 218 votes to two. This Nicene Creed became the official position of the universal Church and remains the creed of both the Roman and Orthodox Churches to this day.
The Nicene Creed
Here is the text of the Creed as originally passed by the Council of Nicaea in 325. The final paragraph is specifically directed against the Arians.
We believe in one God, the Father Almighty, maker of all things, both visible and invisible.
And in one Lord, Jesus Christ, the Son of God, begotten of the Father God of God and Light of Light, very God of very God, begotten and not made, being of one substance with the Father, by whom all things were made; who for us men and for our salvation came down and was made flesh, made man, suffered and rose again on the third day, went up into the heavens and is to come again to judge the quick and the dead; And in the Holy Spirit.
But the Holy Catholic and Apostolic Church anathematises those who say that there was a time when the Son of God was not, and that he was not before he was begotten, and that he was made from that which did not exist; or who assert that he is of other substance or essence than the Father, or is susceptible of change.