The Fourth Ecumenical Council – Chalcedon (451 A.D.)

 Key Issue: The Two Natures of Christ

The Council of Chalcedon addressed and settled the profound theological question: How are Christ’s divinity and humanity related in one person? This council clarified and defended the teaching against two major errors: Nestorianism (dividing Christ into two persons) and Eutychianism (confusing or merging his natures into one).

Chalcedonian Definition

Chalcedon’s central teaching, also called the “Chalcedonian Definition,” proclaimed:

• Christ is one Person (not two).

• He is fully God and fully man.

• He exists in two natures—divine and human—“without confusion, change, division, or separation.”

• The unique properties of each nature are preserved; neither is absorbed into the other, nor diminished.

• The two natures unite perfectly in one Person and one Hypostasis (a term the Church Fathers used for concrete individual existence in the Trinity and Incarnation).

Why Is This Theologically Important?

1. Orthodox Christology

This definition guards the full truth that Jesus is both God and man, enabling him to act as mediator—bridging the infinite gap between God and the human race. This balanced formula ensured he could truly represent both God (able to save) and humanity (able to suffer and die for humans).

2. Protects Mystery of the Incarnation

By rejecting Nestorian division (making two persons) and Eutychian confusion (blending natures), the council preserved the mystery and totality of the Incarnation. Jesus is not a hybrid, nor a divided being, but uniquely united.

3. Foundation for Christian Doctrine

The Chalcedonian formula became central for Orthodox, Catholic, and most Protestant doctrine. It is recited in creeds and forms the backbone for understanding redemption, sanctification, and the sacraments.

Theological Conclusions

• Christ is one Person in two complete natures: divine and human.

• His natures are united perfectly—without mixing or splitting.

• He remains fully God and fully man forever, making possible true atonement and resurrection for human beings.

• This doctrine is the cornerstone of Orthodox Christology and continues to shape Christian faith today

What Does “Without Confusion, Change, Division, or Separation” Mean? (Chalcedonian Christology)

The Council of Chalcedon taught that Jesus Christ is one Person in two natures—divine and human—"without confusion, without change, without division, without separation." Here’s what each phrase means:

• Without confusion: Christ’s divine and human natures are not mixed or blended together into something new. He isn’t a hybrid or a being who is half-God and half-human; He is fully God and fully man at the same time.

• Without change: Neither nature is changed or altered by the union. Christ’s divinity remains fully divine, and His humanity remains fully human—they do not morph into something else.

• Without division: The two natures don’t divide Christ into two separate beings or persons. Jesus is not sometimes acting as God and sometimes as a different, separate man; He is always the one and same Christ acting in both natures together.

• Without separation: Though distinct, the two natures are never separated or apart from one another. From the moment of the Incarnation, the divine Son is forever united to real humanity—it’s one permanent union in one person.sola+2​

Why Does This Matter for Salvation and Worship?

This safeguard is essential for Christian faith:

• Salvation: If Jesus were not fully God and fully man, He could not truly bridge the gap between God and humanity. Only as one person, truly God (able to save) and truly human (able to represent us and suffer with us), can He offer a perfect sacrifice that redeems real human beings.

• Worship: Christians worship Jesus as Lord because He is God. Affirming both natures ensures our worship honors the true God who became man for our sake, not a mixture, not a lesser being, and not a divided figure. This guards against error and keeps the faith centered on who Christ really is.

In sum: The Chalcedonian Definition means Jesus Christ is one Person with two complete, unconfused, unchanged, indivisible, and inseparable natures—so He can be wholly present to save and worthy to worship as both God and man.