The last of the Greek fathers, John was born in Damascus, Syria. He succeeded his father as chief representative of the Christian community to the caliph in Damascus, then under Islamic rule. However, after serving some years, he was forced to resign in 719 because of his faith. He entered a monastery in the mountain wilderness between Jerusalem and the Dead Sea, and lived there until his death. As a priest, he devoted himself to prayer and writing, producing 150 works on theology, philosophy and religious education, as well as a defense of the veneration of icons and numerous hymns. His work was widely cited in the Middle Ages. Pope Leo XIII declared him a doctor of the church in 1890.