John's family had a high position in the Muslim rulers of Damascus, and on the death of his father was made chief councillor of Damascus. Around this time, heresy of iconoclasm began to appear, which disturbed the Church of the East. In 726, in disregard of the protests of Germanus, Patriarch of Constantinople, Emperor Leo the Isaurian issued his first edict against the veneration of images and their exhibition in public places. A talented writer and in the secure surroundings of the caliph's court, John de Damascene initiated his literary defense against the monarch in three Apologetic Treatises against those Decrying the Holy Images. This was the earliest of his works and the one which earned him a reputation.
After a forged letter was sent by Leo the Isaurian, John's hand was cut off, but was restored after fervent prayer before an icon of the Virgin Mary. The caliph, convinced of his innocence, wished to reinstate him, but John then retired to the Monastery of Saint Sabbas near Jerusalem, where he continued to produce a stream of commentaries, hymns and apologetic writings, including the Oktoechos (the Church's service book of eight tones) and An Exact Exposition of the Orthodox Faith, a summary of the dogmatic writings of the Early Church Fathers.