Final answer:
St John Damascene defended the use of icons based on Jesus Christ's incarnation, arguing that God's physical manifestation allowed for visual representation, which supports faith and triumphs over evil.
Step-by-step explanation:
St John Damascene offered a robust defense of icons during the Iconoclastic Controversy, a religious dispute in 8th and 9th century Byzantine Empire about the use of religious images. His reasoning was based fundamentally on the Incarnation, the Christian belief that Jesus Christ, as God made flesh, could be depicted visually because he had taken on a visible form. St John argued that if God had allowed Himself to be seen, and by extension represented, in the physical form of Jesus, then creating images was a way of honoring this divine manifestation. He saw icons as a form of triumph and celebration over the forces of evil, indicating the ultimate victory of the faithful. This theological argument complemented the innate human affection for images, which also played a role in the triumphant return to the use of icons after the end of the controversy in 843 CE.