http://www.newadvent.org/cathen/07620a.htm
"To Moslems, any kind of picture, statue, or representation of the human form is an abominable idol."
There seems to have been a dislike of holy pictures, a suspicion that their use was, or might become, idolatrous among certain Christians for many centuries before the Iconoclast persecution began (see IMAGES, VENERATION OF). The Paulicians, as part of their heresy held that all matter (especially the human body) is bad, that all external religious forms, sacraments, rites, especially material pictures and relics, should be abolished.
Eastern monasticism was steadfastly loyal to the old custom of the Church. Leo therefore joined with his Iconoclasm a fierce persecution of monasteries and eventually tried to suppress monasticism altogether...
...Meanwhile the persecution raged in the East. Monasteries were destroyed, monks put to death, tortured, or banished. The Iconoclasts began to apply their principle to relics also, to break open shrines and burn the bodies of saints buried in churches. Some of them rejected all intercession of saints. These and other points (destruction of relics and rejection of prayers to saints), though not necessarily involved in the original programme are from this time generally (not quite always) added to Iconoclasm.
...The emperor's anger against image-worshippers was strengthened by a revolt that broke out about this time in Hellas, ostensibly in favour of the icons. A certain Cosmas was set up as emperor by the rebels. The insurrection was soon crushed (727), and Cosmas was beheaded. After this a new and severer edict against images was published (730), and the fury of the persecution was redoubled.
...Pope Gregory II died in 731. He was succeeded at once by Gregory III, who carried on the defence of holy images in exactly the spirit of his predecessor.
...In 731 Gregory III held a synod of ninety-three bishops at St. Peter's in which all persons who broke, defiled, or took images of Christ, of His Mother, the Apostles or other saints were declared excommunicate. Another legate, Constantine, was sent with a copy of the decree and of its application to the emperor, but was again arrested and imprisoned in Sicily. Leo then sent a fleet to Italy to punish the pope; but it was wrecked and dispersed by a storm. Meanwhile every kind of calamity afflicted the empire; earthquakes, pestilence, and famine devastated the provinces while the Moslems continued their victorious career and conquered further territory.
Leo III died in June, 741, in the midst of these troubles, without having changed policy. His work was carried on by his son Constantine V (Copronymus, 741-775), who became an even greater persecutor of image-worshippers than had been his father. As soon as Leo III was dead, Artabasdus (who had married Leo's daughter) seized the opportunity and took advantage of the unpopularity of the Iconoclast Government to raise a rebellion. Declaring himself the protector of the holy icons he took possession of the capital, had himself crowned emperor by the pliant patriarch Anastasius and immediately restored the images. Anastasius, who had been intruded in the place of Germanus as the Iconoclast candidate, now veered round in the usual Byzantine way, helped the restoration of the images and excommunicated Constantine V as a heretic and denier of Christ. But Constantine marched on the city, took it, blinded Artabasdus and began a furious revenge on all rebels and image-worshippers (743).
The Paulicians were now treated well, while image-worshippers and monks were fiercely persecuted. Instead of paintings of saints the churches were decorated with pictures of flowers, fruit, and birds, so that the people said that they looked like grocery stores and bird shops. A monk Peter was scourged to death on 7 June, 761; the Abbot of Monagria, John, who refused to trample on an icon, was tied up in a sack and thrown into the sea on 7 June, 761; in 767 Andrew, a Cretan monk, was flogged and lacerated till he died (see the Acta SS., 8 Oct.; Roman Martyrology for 17 Oct.); in November of the same year a great number of monks were tortured to death in various ways (Martyrology, 28 Nov.). The emperor tried to abolish monasticism (as the centre of the defence of images); monasteries were turned into barracks; the monastic habit was forbidden; the patriarch Constantine II was made to swear in the ambo of his church that although formerly a monk, he had now joined the secular clergy. Relics were dug up and thrown into the sea, the invocation of saints forbidden. In 766 the emperor fell foul of his patriarch, had him scourged and beheaded and replaced by Nicetas I (766-80), who was, naturally also an obedient servant of the Iconoclast Government.
The Empress Irene was regent for her son Constantine VI (780-97), who was nine years old when his father died. She immediately set about undoing the work of the Iconoclast emperors. Pictures and relics were restored to the churches; monasteries were reopened. Fear of the army, now fanatically Iconoclast, kept her for a time from repealing the laws...