Apologists for Christianity argue that an alleged Jesus Christ began the Christian church when he commissioned a man named Peter [sic] to control the keys to his kingdom (Matt 16:18). While this requires further discussion, it is imperative at this time to debunk the idea that literalists put forth about Jesus creating a church (ekklesia in the ancient Greek meant an assembly not a church). The Emperor Constantine (lived from 274 to 337) in the fourth century CE was tired of the bloodshed and wars led by bishops of rival factions each known as “Christian” (modern transliteration) but not of the same ideology.
Constantine, who was never a Christian (that is a legend created in 397 CE) was worried about the dispute between Arianism and other factions (Arianism was the most popular version but was opposed by various old men who would not accept the rubrics of this practical faith but preferred to incorporate Mithraism and pantheons of gods [led by the quite unholy bishops of Hippo in Africa] as saints instead). Arianism was the belief that Jesus was a created being. The famous phrase they were disputing was, “There was when He was not.” This was in reference to Jesus and was declared heretical by the council and thus resulted in the following words about Christ in the Nicene Creed, “God from true God…from the Father…not made”. It was determined by the council that Christ was homoousia (meaning, one substance with the Father) that led to an intense bloodshed even among the bishops. The Arian document was torn to shreds in the sight of everyone present at the council (see Elwell, Evangelical Dictionary of Theology). Constantine (and the Council of Nicaea, for that matter) had virtually nothing to do with the forming of the canon. It was not even discussed at Nicaea. The Council of Nicaea affirmed the deity of Jesus Christ and established an official definition of the Trinity based on the earlier Trinity of ancient pagan Mycenae (c. 1500-1400; cf. National Museum, Athens) transmogrifying the three goddesses into the deity of The Father, Son, and Holy Spirit under one Godhead, having three co-equal and co-eternal Persona (an idea even older, dating before the rise of Akkadia). The word “Trinity” does not appear in any ancient “christian” scroll nor any early bible through the Reformation.
It was Constantine who called the Council of Nicaea. Not the bishops. He recognized that a schism in the Christian church would be just one more destabilizing factor in his empire, and he moved to solve the problem. While he had encouragement from men like Hosius, bishop of Cordova, and Eusebius of Caesarea, Constantine was the one who officially called for and presided over the council and selected statements that would ensure harmony in his empire (See Philip Schaff’s comments in his History of the Christian Church (Grand Rapids: Eerdmans, 1985), 3:335; Latin translations about this Council are bad at best).
The Council of Nicaea was never popular with anyone. During the course of the decades following Nicaea, Athanasius, who had become bishop of Alexandria shortly after the council and supported the heretical view that Jesus was co-equal with the Father, was removed from his see five times, once by force of 5,000 soldiers coming in the front door while he escaped out the back! Hosius, now nearly 100 years old, was likewise forced by imperial threats to compromise and give place to Arian ideas, which were supported by Constantine and his successors. At the end of the sixth decade of the century, it looked as if Nicaea would be defeated. Jerome would later describe this moment in history as the time when “the whole world groaned and was astonished [sic] to find itself Arian.” See: Jerome, Adversus Luciferianos, 19, Nicene and Post Nicene Fathers, Series II, 6:329.
The bishop of Rome never attended the council. He sent two representatives, and few bishops recognized Rome as superior, primary, or titular. Constantinople was hailed as the “First Seat” of the emerging church especially when it came to arguments over language (Greek words like “essence” (ousia), “substance” (hypostasis), “nature” (physis), “person” (prosopon) bore a variety of meanings drawn from pre-Christian philosophers. Weak in linguistic skills (common in any culture that is attempting to learn a non-native language) entailed misunderstandings until they were cleared up. The word homoousia, in particular, was initially disliked by many bishops because of its associations with Gnostic heretics (who rightfully used it in their theology which antedated most of what would become official church sanctioned ontology and theology), and because it had been condemned at the 264–268 Synods of Antioch–the primary seat of authority). See: Theodoret, General Council of Nicæa Book 1 Chapter 6 of his Ecclesiastical History; The Epistle of the Emperor Constantine, concerning the matters transacted at the Council, addressed to those Bishops who were not present Book 1 Chapter 9 of his Ecclesiastical History, a 5th century source.
All “Christians” called themselves “Catholic” meaning a universal accepting of the biblical Jesus–very few recognized Rome save for the messengers and deputies sent out by Rome in quest of wrestling the authority of the other bishops away from the Emperor who lived in the East. See: Sozomen, Of the Council convened at Nicæa on Account of Arius Book 1 Chapter 17 of his Ecclesiastical History, a 5th century source but an apologetic which would leave the womanizing “Saint” Augustine of Hippo in their debt after his conversation with Ambrose of Milan at the scolding of his mother Helen whom Augustine would raise to the altar as a saint over the protests of most bishops and priests who noted that Augustine was never a holy man but continued many of his pagan practices even once he installed himself into the See of Hippo.