Why did some Eastern churches reject the decisions of the Council of Chalcedon?

Some Eastern churches, now known as the Oriental Orthodox communion, rejected the decisions of the Council of Chalcedon (451) primarily because they viewed its "two natures" formula as a betrayal of the Christology of St. Cyril of Alexandria.12

While the Council of Chalcedon affirmed that Christ possessed two distinct natures—divine and human—in one person, these churches upheld a miaphysite position. They argued that through the mystery of the Incarnation, Christ’s humanity and divinity were united in a single nature without being separated or commingled.123

Because they rejected the Chalcedonian definition of "two natures," these churches were often disparagingly labeled as monophysites and branded as heretics by the Roman and Greek churches. However, the non-Chalcedonian churches consistently refuted this label, maintaining that their theology preserved the reality of Christ’s humanity while emphasizing the unity of his person. This schism persisted for centuries, though modern ecumenical dialogue has led to a greater understanding that the division was largely based on terminology and historical misunderstanding rather than fundamental theological disagreement.132