Letter to Boris I, King of Bulgars

This extended letter to the khan of the Bulgars attempts to encapsulate to the essence of Christian faith and the divine guidance it offers to believers, emphasizing the significance of virtues and the importance of ecumenical councils in establishing orthodox teachings. It outlines the foundational beliefs encapsulated in the Symbol of Faith, affirming the Trinity and the dual natures of Christ. The text recounts the proceedings and outcomes of seven significant ecumenical councils, detailing their collective efforts to combat heresies, affirm the nature of God, and establish the worship of sacred images in Christianity, ultimately underscoring the unity and divinity of the Christian faith.