The Impact of the Council of Chalcedon and Schisms in the East (AD 451–650)

The Council of Chalcedon, convened in AD 451, was one of the most significant ecumenical councils in Christian history. It clarified the doctrine of Christ's dual nature—fully divine and fully human—within one person, a teaching that would form a cornerstone of Chalcedonian Christianity. However, this doctrinal definition also resulted in lasting schisms in the Eastern Church. Several communities, collectively referred to as the “non-Chalcedonian” Churches, rejected the council's decisions, leading to deep theological and ecclesial divisions that persist to this day. This article explores the theological debates at Chalcedon, the subsequent schisms, and their implications for the broader Christian world, particularly the St. Thomas Christians and their connections with the Church of the East.

The 5th century was marked by intense debates about the nature of Christ, particularly how his divine and human natures coexisted. The controversy had already led to earlier councils, including the First Council of Nicaea (AD 325) and the First Council of Ephesus (AD 431). At Ephesus, Nestorianism—a doctrine that emphasized the separation between Christ's divine and human natures—was condemned, affirming Mary as Theotokos (“God-bearer”)⁽¹⁾.

In contrast, Monophysitism arose as a reaction to Nestorianism. This doctrine, championed by Eutyches and others, held that Christ's human nature was subsumed into his divine nature, resulting in only one nature (“mono-physis”). This teaching sparked controversy, especially in Alexandria, a theological center of Monophysite thought, and led to the convening of the Council of Chalcedon⁽²⁾.

The Council of Chalcedon, convened by Emperor Marcian, sought to resolve the Christological debates once and for all. The council produced the Chalcedonian Definition, which affirmed that Christ exists in two natures, “unconfusedly, unchangeably, indivisibly, inseparably,” united in one person (hypostasis)⁽³⁾. This definition rejected both Nestorianism and Monophysitism, aiming for a middle ground that preserved both Christ's full divinity and full humanity.

The council also reaffirmed the authority of the previous councils of Nicaea and Ephesus and canonized the Tome of Leo, a letter from Pope Leo I articulating the two-nature doctrine⁽⁴⁾.

Despite its efforts to unify the Church, the Council of Chalcedon led to significant divisions. Many Eastern Churches, particularly in Egypt, Syria, Armenia, and Ethiopia, rejected the council's teachings. These communities, later called the Oriental Orthodox Churches, argued that Chalcedon's two-nature formula compromised the unity of Christ and aligned too closely with Nestorianism⁽⁵⁾.

Key non-Chalcedonian Churches include:

• Coptic Orthodox Church: Centered in Egypt, the Copts rejected Chalcedon and adhered to Miaphysitism, which holds that Christ has one united nature that is both fully divine and fully human⁽⁶⁾.
• Syriac Orthodox Church: Also known as the Jacobite Church, this community became a stronghold of non-Chalcedonian Christianity in Syria⁽⁷⁾.
• Armenian Apostolic Church: The Armenians also rejected Chalcedon, cementing their distinct ecclesial and theological identity⁽⁸⁾.
• Ethiopian Orthodox Tewahedo Church: This Church retained strong ties to the Coptic Orthodox Church and similarly rejected Chalcedon⁽⁹⁾.

The Chalcedonian schism was not only theological but also deeply political and cultural. The non-Chalcedonian Churches were concentrated in regions where local identities—Egyptian, Syrian, and Armenian—often clashed with Byzantine imperial authority. The council's decisions were perceived by many as an imposition of Constantinople's dominance over the Eastern provinces⁽¹⁰⁾.

The St. Thomas Christians of India, tracing their origins to the Apostle Thomas, were historically connected with the Church of the East, centered in Seleucia-Ctesiphon in the Sasanian Empire. This Church followed the East Syriac tradition and had distanced itself from the Roman-Byzantine theological debates by aligning with Nestorianism⁽¹¹⁾. While not directly involved in the Chalcedonian controversy, the St. Thomas Christians were indirectly affected by the schisms as their relationship with the broader Christian world evolved.

The theological positions of the non-Chalcedonian Churches resonated with some aspects of East Syriac Christology, particularly their shared resistance to Byzantine dominance. Over time, however, the St. Thomas Christians maintained closer ties with the Church of the East rather than the Oriental Orthodox Churches, further distinguishing their theological and liturgical identity⁽¹²⁾.

The Chalcedonian schisms also contributed to the isolation of the St. Thomas Christians. As the Byzantine and Persian Empires vied for control over Christian communities, the Indian Church remained geographically and theologically distinct. This isolation allowed the St. Thomas Christians to preserve their unique traditions but also limited their influence within the broader Christian world⁽¹³⁾.

The schisms following Chalcedon entrenched divisions within Eastern Christianity. The rise of Islam in the 7th century further exacerbated these divisions, as many non-Chalcedonian Churches, such as the Coptic and Syriac Orthodox Churches, found themselves under Islamic rule and increasingly disconnected from Chalcedonian Christianity⁽¹⁴⁾.

The Chalcedonian and non-Chalcedonian Churches developed distinct theological traditions over the centuries. While ecumenical dialogues in the 20th and 21st centuries have sought to reconcile these differences, the divisions initiated by Chalcedon remain a defining feature of Christian history⁽¹⁵⁾.

The Council of Chalcedon was a pivotal moment in Christian history, solidifying the doctrine of Christ's two natures but also precipitating one of the most enduring schisms in the Church. For the Chalcedonian Churches, the council represented a victory for orthodoxy and unity. For the non-Chalcedonian Churches, it marked a departure from what they viewed as the true faith. The impact of Chalcedon extended far beyond its immediate aftermath, influencing the theological, cultural, and political trajectories of Christianity in the East. The St. Thomas Christians, while geographically distant from the core of the schisms, were nevertheless shaped by the broader currents of Eastern Christianity, navigating their own path amidst these profound divisions.

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