Article 4: Fourth Century Heresies — Arianism and the Divinity of Christ

Article 4: Fourth Century Heresies — Arianism and the Divinity of Christ

1. Historical Background

The fourth century (roughly AD 300–400) opened with a dramatic change: after centuries of persecution, the Edict of Milan in AD 313 under Emperor Constantine made Christianity legal across the Roman Empire. Christianity quickly moved from a persecuted minority faith to one openly favoured by the state.

This new freedom brought a new kind of danger. With the Church no longer under threat of death, its internal debates could now spread across the whole empire, openly and publicly, and even draw in the emperor himself. The most serious of these debates concerned a question at the very heart of the Christian faith: was Jesus Christ truly, fully God — or something less?

2. Main Heresies of This Period

• Arianism, named after Arius, a priest from Alexandria, was by far the most significant heresy of this century. Arius taught that the Son of God was not eternal but was created by the Father — famously summarised in the slogan "there was a time when he was not." In this view, Christ was a supremely exalted creature, but not truly and eternally God in the same sense as the Father.

This single teaching set off the largest and most consequential doctrinal crisis the early Church had yet faced, touching nearly every province of the empire.

3. Why This Teaching Was Wrong

From Scripture:

• John opens his Gospel by stating that the Word was with God and was God, and that all things were made through Him, with nothing made without Him (John 1:1–3, NIV) — meaning the Word cannot Himself be one of the created things.
• Jesus said plainly, "I and the Father are one" (John 10:30, NIV), pointing to a unity of being between Father and Son, not a creature honouring its creator from a distance.
• Paul describes Christ as existing before all things, with all things holding together in Him, and as the visible image of the invisible God (Colossians 1:15–17, NIV) — language of supremacy and eternity, not of being first among created beings.
• The writer of Hebrews describes the Son as the exact representation of God's being (Hebrews 1:3, NIV), a description that cannot fit a created being, however exalted.

From the teaching of the early Church: Bishops from across the empire, gathering in the first major worldwide council, tested Arius's teaching against Scripture and the faith received from the apostles, and rejected it almost unanimously.

Why it was dangerous: If Christ is a creature, however glorious, then He cannot fully reveal God, and He cannot accomplish a work of salvation that only God Himself can do. Worshipping Him would also mean worshipping a created being — something Scripture forbids. Arianism, left uncorrected, would have quietly turned Christian worship of Christ into idolatry.

4. How the Church Responded

• In AD 325, Emperor Constantine convened the Council of Nicaea, the first council to gather bishops from across the whole Christian world. The council formally rejected Arius's teaching.
• The council produced the Nicene Creed, declaring the Son to be "of one substance" with the Father — using the Greek word homoousios to make unmistakably clear that the Son shares the very same divine essence as the Father, not merely a similar one.
• Athanasius, a young deacon at the council who later became Bishop (Pope) of Alexandria, became the tireless lifelong defender of this Nicene faith. He was exiled from his see five times by emperors sympathetic to Arianism, yet never abandoned the teaching that Christ is truly God — a stand later remembered by the phrase Athanasius contra mundum, "Athanasius against the world."
• The controversy did not end immediately at Nicaea; further debate continued for decades until the Council of Constantinople in AD 381 confirmed and expanded the Creed, also affirming the full divinity of the Holy Spirit.

5. What Happened Later

• Arianism did not disappear quickly. Arian missionaries converted several Germanic peoples, including the Goths and Vandals, and Arian Christianity survived among these groups for a few more centuries even after being rejected by the wider Church.
• The Nicene Creed became, and remains, one of the most universally shared statements of Christian faith, recited across almost every Christian tradition to this day.
• Teachings that deny Christ's full, eternal divinity in an Arian-like way have continued to reappear in various forms into the modern era, a theme this series returns to in its final article.

6. Lesson for Christians Today

• Councils and creeds, formed by bishops working together rather than by any one individual, remain a valuable way the Church tests and confirms right belief.
• The full, eternal divinity of Jesus Christ is not a minor detail; it stands at the very centre of the Christian faith and its hope of salvation.
• Athanasius's example shows that standing firm for the truth, even when it is unpopular or costly, can be an act of great faithfulness.

A Coptic Orthodox note: Athanasius served as the twentieth Pope of Alexandria and is deeply honoured in the Coptic Church as a "Pillar of Faith." The Nicene Creed he defended is recited in the Coptic Divine Liturgy to this day, connecting Coptic worshippers directly to this fourth-century defence of Christ's true divinity.

7. Short Summary

• The fourth century began with Christianity's legalisation, allowing doctrinal debates to spread across the whole empire.
• Arianism taught that Christ was a created being, not eternally God.
• Scripture affirms that the Son is eternal, uncreated, and shares the Father's very being.
• The Council of Nicaea (AD 325) rejected Arianism and produced the Nicene Creed.
• Athanasius became the lifelong defender of Nicene faith, enduring repeated exile.
• The Council of Constantinople (AD 381) later confirmed and completed this teaching.
• Christ's full divinity remains central to salvation, and the Nicene Creed remains a shared confession across Christian traditions today.