The Truth About Nestorianism–And Why It Still Matters

By Aaron Schuck

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Of all the heresies that threatened the early Church, none attacked the person of Christ and the role of the Blessed Virgin more insidiously than Nestorianism. It is rarely named today. But its effects are everywhere.

This ancient error, condemned at the Council of Ephesus in 431 A.D., denied that Mary could be called the Mother of God–Theotokos in Greek. Nestorius, then Patriarch of Constantinople, taught that Mary was only the “Mother of Christ” (Christotokos), not of God Himself. His argument seemed reasonable to many: God, after all, is eternal. Mary is a creature. How can the finite give birth to the infinite?

But the Church responded with unflinching clarity: you cannot divide Christ. You cannot fracture His person. If you deny Mary is the Mother of God, you do not merely demote Mary. You dismantle the Incarnation.

The Heresy Explained

Nestorianism was not a denial of Christ’s divinity. It was a denial of His unity. Nestorius insisted that Jesus had two persons–one human, one divine–joined only in moral or relational union. But orthodox Christology, rooted in St. Cyril of Alexandria and later confirmed at Chalcedon, proclaimed that Christ is one divine person with two natures–human and divine–united without confusion, separation, or division.

The error may seem technical. But it cuts to the heart of our salvation. If Christ is not one person, then He did not truly assume our nature. If His natures are not united in one who, then the Cross is meaningless and the Eucharist a lie.

The question was not about titles. It was about reality.

Theotokos Is a Christological Statement

When the Church called Mary Theotokos, it was not exalting Mary above her place. It was defending the truth about Christ. The word means “God-bearer”–not in eternity, but in time. She bore in her womb not a separate human person connected to God, but God Himself incarnate.

If Jesus Christ is truly God, and if He was born of her, then Mary is the Mother of God. To deny this is not to be cautious. It is to be heretical.

This is why the people of Ephesus famously gathered in the streets after the council’s ruling, chanting, “Theotokos! Theotokos!” It was not abstract devotion. It was theological warfare. They knew that in defending Mary’s title, they were defending the unity of Christ–and their hope of salvation.

Why Nestorianism Lingers

Today, Nestorianism is not taught by name. But it is lived in instinct. Many Catholics speak of Christ as if His divinity and humanity toggle on and off, like modes. Others reduce Mary to a genetic conduit–as if God simply used her womb and discarded her afterward. Some reject Marian devotion entirely, claiming that it distracts from Christ.

But all these errors come from the same root: the failure to understand the Incarnation as real, total, and permanent.

Christ is one person. And that person is divine. The humanity He took on from Mary is not a mask or a phase. It is His forever. That means what Mary gave Him–her flesh, her milk, her embrace–was given to God. And what He offered on the Cross, He received from her.

To separate Mary from God is to separate Christ from Himself.

Why It’s Important

The Church did not invent doctrine in 431 A.D. It preserved it. And the faithful do not honor Mary to compete with Christ. We honor her because Christ cannot be understood apart from her. He chose to enter the world through her. And He remains united to the humanity He took from her for all eternity.

In a culture that sees motherhood as a burden and faith as an abstraction, Nestorianism reemerges every time we separate the spiritual from the physical, the divine from the maternal, or Christ from His own flesh.

To call Mary Theotokos is not to idolize her. It is to proclaim–without apology–that the eternal Son of God became man in her womb, was born of her, and remains fully human and fully divine forever.

To get Mary wrong is to get Christ wrong. And to get Christ wrong is to lose everything.