Which theological concept was clarified at the Council of Chalcedon?

The Council of Chalcedon, convened in 451 AD, was a significant ecumenical council in the history of Christianity, primarily addressing the nature of Christ. One of its most crucial clarifications was the doctrine of the dual nature of Christ, affirming that Jesus Christ is recognized as both fully divine and fully human. This doctrine was articulated in the Chalcedonian Definition, which stated that Christ exists in two natures, unconfusedly, unchangeably, indivisibly, and inseparably.

This clarification was essential in countering various heretical teachings that either emphasized Jesus' divinity at the expense of his humanity or vice versa. By affirming that Christ possesses both natures simultaneously, the council helped establish a foundational tenet for orthodox Christian belief about the person of Jesus. This dual nature becomes critical for understanding how Jesus represents both God and humanity, particularly in the context of salvation and the nature of the Trinity.

The other theological concepts listed, while significant in their own right, were not the focus of the Council of Chalcedon. The nature of the Church, the relationship of faith and works, and the concept of original sin were addressed in different contexts and councils, but Chalcedon specifically sought to