How to respond to someone who says Christ's composite nature is a third nature?

By CopticBot.ai (Coptic Space Inc.) · Last reviewed 2026-10-10

When addressing the claim that Christ's nature is a "third nature" (a tertium quid), you must firmly clarify the Coptic Orthodox understanding of Miaphysitism. This claim is often a misunderstanding or a deliberate misrepresentation by supporters of the Council of Chalcedon or heretics who confuse our faith with Eutychianism.

Here is how to respond based on the teachings of St. Cyril of Alexandria and our theological tradition:

1. Reject the Idea of a "Mixture" or "Confusion"

The most important point to establish is that we do not believe the Divinity and Humanity were mixed like water and wine to create a third, different substance. As St. Cyril taught, the union is unconfused and immutable.

• The Response: We do not believe in a "third nature." A third nature would imply that Christ is no longer consubstantial (of the same essence) with the Father in His Divinity, or consubstantial with us in His Humanity. If Christ were a "third nature," He could not save us because He would not be truly human.

2. Explain "One Nature out of Two"

Explain that the term "Composite Nature" does not mean a new hybrid, but a Union.

• The Response: When we use the formula of St. Cyril—Mia Physis tou Theou Logou Sesarkomene (One nature of God the Word Incarnate)—the "One Nature" refers to a unified reality where the two natures (Divinity and Humanity) continue to exist in their full integrity without being absorbed or altered.
• The Analogy: Use the analogy of the union of the soul and the body. A human being is one nature/person, yet the soul remains soul and the body remains body. They do not merge to become a "third" substance that is neither soul nor body; rather, they form one composite human nature.

3. Address the Charge of "Quaternity"

Heretics often claim that if we do not distinguish "two natures after the union," we either lose the humanity or create a fourth person in the Trinity.

• The Response: St. Cyril argues that it is actually the Nestorian view (separating the natures) that risks making the Trinity a "Quaternity" by treating the humanity as a separate entity or person. By maintaining "One Nature" (a natural union), we preserve the fact that there is only one Subject, the Word of God, who suffered in the flesh.

4. Direct Refutation of Heresy

Be straightforward in distinguishing our faith from that of the heretics:

• Against Eutyches: Eutyches claimed the humanity was swallowed up by the divinity. We condemn this. We believe the flesh remains flesh.
• Against Nestorius: Nestorius claimed the natures were merely "associated." We believe in a true, hypostatic union.
• Against the Diophysites (Chalcedonians): They claim we are "monophysites" (one single nature). This is false. We are Miaphysites (one united nature).

Summary for your dialogue:

"We do not confess a third nature. We confess that Christ is 'consubstantial with the Father according to the Divinity and consubstantial with us according to the Humanity.' The term 'Composite Nature' simply describes the reality that the Logos took flesh and became man while remaining God. The properties of each nature remain distinct and active within the union, without separation and without change."