How did the relationship between church and state work in the Byzantine Empire?

In the Byzantine Empire, the relationship between church and state was defined by the ideal of symphōnia, or "harmony," where the civil and ecclesiastical functions of Christian society were intended to work together as a unified whole.12

The Concept of Symphony

The Byzantine view, rooted in the theology of Eusebius of Caesarea, held that the emperor served as God’s representative on earth, acting as the protector of the church and the preserver of the unity of the faith. While the emperor often held significant influence over church administration—leading some to use the term caesaropapism—this label is considered inaccurate by many scholars. The emperor did not have the authority to define the content of the faith, and the church maintained its own authority over spiritual doctrine and order.123

Governance and Resistance

The emperor and the patriarch were often described as a dyarchy, functioning like the soul and body of a single organism. Although the hierarchy of the church often lacked legal mechanisms to oppose imperial power, the church and laity frequently resisted imperial decrees they deemed detrimental to the faith, such as during the Iconoclastic Controversy. The 9th-century Epanagoge further codified this relationship, directing the patriarch to support the truth and defend holy teachings without fear of the emperor.321