The Third Ecumenical Council – Ephesus (431 A.D.)

 Key Issue: The Unity of Christ’s Person and the Title Theotokos

Let’s break down the background, decision, and theological meaning of the Council of Ephesus, step by step.

Historical Context

In the early 400s, controversy swirled around Nestorius, Patriarch of Constantinople, who argued that Christ was essentially two "persons"—one divine (the Word) and one human (Jesus). Because of this duality, Nestorius refused to call Mary "Theotokos" (Greek for "God-bearer"), preferring "Christotokos" ("Christ-bearer") instead.

St. Cyril of Alexandria led the opposition, insisting on the unity of Christ—that God the Word truly became man, uniting divinity and humanity in one Person.

Decisions of the Council

• Condemned Nestorianism: Ephesus rejected any division in Christ’s person. There are not two separate "persons," but one single Person who is both divine and human at all times.

• Affirmed Mary as Theotokos: Since the one Jesus Christ Mary bore is truly God incarnate, she is rightly called "God-bearer."

Why Does This Matter theologically?

1. Unity of Christ’s Person

Affirming Jesus as one undivided Person is crucial: it means every act of Jesus—healing, suffering, dying, rising—truly belongs to both God and man. Salvation relies on this unity: if Christ were two separate entities, He could not bridge divinity and humanity.

2. Theotokos safeguards Incarnation

Calling Mary “Theotokos” expresses the mystery that God Himself entered the world as a real human; He wasn’t just "inhabiting" a man or switching between two personalities. This strengthens orthodox belief in the Incarnation.

3. Impact on Devotion and Doctrine

Mary’s title as Theotokos became central in Christian prayer and liturgy, reminding believers of the true mystery of God’s self-giving.

Theological Conclusions

• Jesus Christ is one Person: both fully God and fully human, united without division or confusion.

• Mary is truly Theotokos: she gave birth to God incarnate; this affirms the reality of the Incarnation.

• Nestorianism rejected: any teaching dividing Christ’s person undermines salvation and true union with God.

It is important for salvation that Christ is one Person and not two separate ones because only as a single, unified Person can Jesus truly represent both God and humanity in everything He does. If there were two separate persons—one divine and one human—then Christ’s actions (such as suffering, dying, and rising again) would not fully belong to both God and man. Only the one Person of the Incarnate Son, who is fully God and fully man, can unite humanity to God and make salvation real. This unity means that when Jesus died and rose, it was truly God-in-the-flesh acting for us, making redemption personal and effective for the whole human race.