The Trinitarian controversy lasted from AD 318 to AD 382, concluding with the Council of Constantinople of AD 381, at which the definitive theological position of the Church on the Trinity was formally articulated. That position holds that God comprises one nature or substance, which is divine, in three divine persons, or entities. Whether or not that position makes sense as a theological mystery, a fundamental article of faith, or a nonsense statement must be set aside for the moment. What is important is that the Church fathers who found meaning in it did so in order to lend authority and rationality to the institutional character of the organization that was taking shape in the fourth century.
The first phase Trinitarian controversy erupted soon after the emperor Constantine embraced Christianity and stopped the policy of persecution of the Christians in AD 313. However, between that time and 325, the good church fathers were preoccupied with rationalizing and identifying the content of Christian doctrine. One such effort--apparently well-intentioned--was undertaken by Bishop Arius of Alexandria, who asserted the absolute character, or unique oneness, of God. So far, so good, for God is to be conceptualized as distinct and distinctively superior in his eternal glory to mere mortal man. But a problem arises with the looming figure of Jesus Christ, originator of Christianity. If God is one, perfect, etc., and if Christ as the Son of God is to be considered a palpable, human, historical being, it follows by Arian reasoning that Christ, though an extraordinary human being, cannot be considered God, since man and God have distinct categories of existence, with man, even the most extraordinary, subsidiary to God. That thesis informs a letter written by Arius to a theological colleague: "[T]he Son is not unbegotten, nor a part of the unbegotten in any way, nor of any substratum, that . . . constituted by will and counsel, before times a...