Coucil of Chalcedon 451 AD

Historical Context

Previous Councils

By then year 451 AD, the Christian church had already convened for three councils. Click the tabs below to learn more about the basics of each.

The First Ecumenical Council

The Council of Nicaea was the first major gathering of Christian leaders, called by Emperor Constantine to resolve growing divisions within the Church. One of its main goals was to address the teachings of Arius, a priest who argued that Jesus Christ was not fully divine but rather a created being. This sparked heated debates about Christ’s nature, leading to the rejection of Arianism and the affirmation that Jesus is “of the same substance” as God the Father.


The council’s most enduring legacy is the Nicene Creed, a foundational statement of Christian faith that outlines beliefs in the Trinity: God the Father, Jesus Christ the Son, and the Holy Spirit. By bringing bishops together from across the Roman Empire, Nicaea marked a turning point for Christianity, cementing its theological unity and its growing role within the imperial structure.

The Second Council

The Council of Constantinople was convened by Emperor Theodosius I to address lingering theological disputes following the Council of Nicaea. Chief among these was the question of the Holy Spirit’s divinity, which some groups denied. The council affirmed the Nicene Creed, expanding it to clarify the role of the Holy Spirit as “the Lord, the Giver of Life,” equal with the Father and the Son. This established the doctrine of the Trinity more fully.

The council also condemned several heresies, including Apollinarianism, which claimed that Christ lacked a human mind, and reaffirmed the unity of Christ’s divine and human natures. By solidifying Christian orthodoxy and establishing Constantinople as a leading center of the Church, this council further unified doctrine across the empire, setting the stage for future theological debates. Its outcomes are often referred to as the Niceno-Constantinopolitan Creed.

Pictured below is a reconstructed version of the building where this council took place.

By Sébah & Joaillier – Library of Congress[1], Public Domain, https://commons.wikimedia.org/w/index.php?curid=6327634

Council of Ephesus

The Council of Ephesus was called by Emperor Theodosius II to resolve a major theological dispute about the nature of Christ and the role of the Virgin Mary. The controversy centered on Nestorius, the Patriarch of Constantinople, who argued that Mary should be called Christotokos (“Christ-bearer”) rather than Theotokos (“God-bearer”). Nestorius claimed that Christ’s divine and human natures were separate, leading to the accusation that he divided Christ into two persons.


The council condemned Nestorius and affirmed Mary as Theotokos, emphasizing the unity of Christ’s divine and human natures. It reinforced the teachings of Cyril of Alexandria, who argued that Christ is one person with two inseparable natures. While the Council of Ephesus sought to maintain unity, it deepened divisions, laying the groundwork for future conflicts, including the debates leading to the Council of Chalcedon.

The Edict of Milan (313 AD)

Christianity became a legal religion in the Roman Empire, which cleared the way for the upcoming theological debates and councils.

https://medievalmilanetc.wordpress.com/2013/02/04/the-edit-of-milan/
https://urhotheway.com/2021/06/28/st-cyril-of-alexandria/
St. Cyril of Alexandria

St. Cyril’s teachings on Christ’s nature (‘one incarnate nature of God the Word’) set the foundation for later debates. Click here to learn more about important figures involved during this time.

Nestorius

The third council condemned him to affirmed Saint Mary as the Theotokos, which meant to declare the absolute unity of Christ’s divine and human natures.

By Romeyn de Hooghe – Historie der Kerken en ketteren…tot aan het jaar onses Heeren 1688, Public Domain, https://commons.wikimedia.org/w/index.php?curid=53737430
early Christian Stats

Early Christianity in Numbers

Here’s some statistics on for perspective on what the early Christian world would have been like around the time of the Councils.

Learn More about Modern Times

~6 million

Estimated Christian population by 300 AD

Over 50%

Percentage of Roman citizens identifying as Christian by 400 AD

318

Number of bishops at Nicaea (325 AD)

Did You Know?

Fun facts about Early Christian History

By 400 AD, the Bible had been translated into several languages. Greek (known as the Septuagint) was widely used in the Eastern Roman Empire, and Latin translations dominated the West. In Egypt, the Bible was available in Coptic, which is still used as the liturgical language of the Coptic Orthodox Church. In Syriac, translations like the Peshitta were available to communities in the Near East. These translations not only made the scriptures more accessible to the masses, but also were able to allow more to engage in theological debate.

Many bishops disagreed at these councils, and not all of the decisions were unanimous. For example, The Council of Nicaea’s final decision was rejected by a minority group who later became the Arians.

The Council of Chalcedon in 451 AD wasn’t only about theology, but it was also a political power play. Emperor Marcian used the council to bring together the Roman Empire under one set of Christian beliefs, which strengthened Constantinople’s influence as a religious center. At the same time the tensions were high between the powerful churches of Rome and Alexandria. Rome, led by Pope Leo I, pushed for its lead in the Christian world. At the same time Alexandria, which was under Dioscorus, held fast to older traditions rooted in the teachings of the church father St. Cyril of Alexandria. Click here to learn more specifics about what the council covered.