Apologia (also titled De Fide Orthodoxa / An Exact Exposition of the Orthodox Faith)

John of Damascus wrote his Apologia to defend the use and veneration of icons amid iconoclastic controversy in the Byzantine Empire.

He argues that because the Word became flesh in Christ, it is permissible and salutary to depict Christ's human form and to honor images of saints and holy things without worshiping created matter.

The work distinguishes veneration (respect) from latreia (worship due to God alone) and marshals scriptural typology and patristic precedent.

His arguments formed a key part of the later Seventh Ecumenical Council's affirmation of icon veneration.

The Apologia remains a foundational text in Orthodox theology and the history of Christian art and worship.