The Arian controversy was a series of Christian disputes about the nature of Christ that began with a dispute between Arius and Athanasius of Alexandria, two Christian theologians from Alexandria, Egypt. The most important of these controversies concerned the relationship between the substance of God the Father and the substance of His Son. Emperor Constantine, through the Council of Nicaea in 325, attempted to unite Christianity and establish a single, imperially approved version of the faith. Ironically, his efforts were the cause of the deep divisions created by the disputes after Nicaea. These disagreements divided the Church into various factions for over 55 years, from the time of the First Council of Nicaea in 325 until the First Council of Constantinople in 381. There was no formal schism. Inside the Roman Empire, the Trinitarian faction ultimately gained the upper hand through the Edict of Thessalonica, issued on 27 February AD 380 by the then reigning three co-Emperors, which made Nicene Christology the state religion of the Roman Empire, and through strict enforcement of that edict. However, outside the Roman Empire, Arianism and other forms of Unitarianism continued to be preached for some time. The modern Roman Catholic Church and the Eastern Orthodox Church, as well as most other modern Christian sects, have generally followed the Trinitarian formulation, though each has its own specific theology on the matter. History Beginnings The early history of the controversy must be pieced together from about 35 documents found in various sources. The Trinitarian historian Socrates of Constantinople reports that Arius first became controversial under the bishop Alexander of Alexandria, when Arius formulated the following syllogism: "If the Father begat the Son, he that was begotten had a beginning of existence: hence it is that there was when the Son was not. It follows then of necessity that he had his existence from the non-existence"..Bishop Alexander of Alexandria was criticised for his slow reaction against Arius. Like his predecessor, Dionysius, he has been charged with vacillation. According to Eusebius's work, The Life of Constantine, the controversy had spread from Alexandria into almost all the African regions, and was considered a disturbance of the public order by the Roman Empire. Constantine the Great (Constantine I) sent two letters to Arius and Bishop Alexander, asking the religious leaders to stop the controversy. The ongoing controversy led to Constantine's oversight of the First Council of Nicaea. First Council