Nicaea I

Arianism was not simply a mistake by an obscure presbyter. It addressed a genuine theological question: How can the Son be genuinely divine if there is only one God? Arius's answer — the Son is a supremely exalted creature — seemed to protect monotheism. His position had appeal among people trained in Middle Platonic philosophy, where the supreme divine principle was so transcendent that it could not directly touch the material world. A subordinate mediating figure solved this problem neatly.

Alexander of Alexandria's counter-argument was that Arius had destroyed salvation. Christians are baptized into the name of the Son. They pray to Christ. They trust his death for forgiveness and his resurrection for eternal life. If the Son is not truly God — the same God as the Father — then Christian worship is idolatry and Christian salvation is delusion. The stakes were not philosophical but soteriological: what kind of God saves us?

Constantine became involved for primarily political reasons. He had just unified the Roman Empire after years of civil war. A divided Church was a problem for imperial unity. He sent his theological adviser Hosius of Cordoba to mediate, but the dispute proved too deep for letters. Constantine then called a council — the first ever convened by an emperor — at his own expense, paying bishops' travel and accommodation.

At the council itself, the debate was fierce. Arius's allies, led by Eusebius of Nicomedia, initially proposed a creed using only biblical language — but it was rejected by the council majority as allowing Arian reinterpretation. The council then adopted homoousios over the objections of those who feared it implied Sabellianism (collapsing Father and Son into one being). Eusebius of Caesarea, the great church historian, tried to find a middle path but eventually signed the final creed under imperial pressure.

The aftermath was turbulent. Constantine eventually readmitted Arius and turned against Athanasius, who was first exiled in 335. Over the next fifty years, the Arian position enjoyed imperial support under emperors Constantius II and Valens. Athanasius's phrase captures the era: Athanasius contra mundum — Athanasius against the world. The Nicene faith survived not through imperial favor but through the patient theological work of Athanasius and, later, the Cappadocian Fathers (Basil, Gregory of Nazianzus, Gregory of Nyssa).

The council's full vindication came at Constantinople in 381. The phrase often attributed to the period — that the great churches recited the Nicene Creed each Sunday — actually developed gradually over the following century. But by the end of the 4th century, Nicaea had become the non-negotiable doctrinal foundation of orthodox Christianity across Catholic and Eastern churches.