Christian religious pictures and relics as objects of veneration in worship services is the defining issue of the era, as East Roman Emperor Leo III, in undertaking a set of civil reforms, begins to speak out publicly in 726 against the use of sacred pictures, and orders the destruction of the image of Christ at the Chalke palace in Constantinople.
Popular revolts against iconoclasm break out in the late 720s in the Cyclades, Naples, Venice, Rome, and elsewhere.
Many Greek theologians, including John Damascene, react to the new policy by developing an elaborate theory and defense of holy images and their place in worship.
Leo, proclaiming Iconoclasm the official policy of the empire in 730, orders the removal and destruction of sacred pictures in churches.
His policies meet particularly strong opposition from monastic circles.
Pope Gregory II also strongly rejects his efforts to impose Iconoclasm upon areas of Italy under imperial control.
The two outbreaks of Iconoclasm in the Empire during the eighth and ninth centuries are unusual in that the use of images is the main issue in the dispute, rather than a byproduct of wider concerns.
Iconoclasm in Christianity has generally been motivated by a literal interpretation of the Ten Commandments, which forbid the making and worshiping of "graven images".
As with other doctrinal issues in the Byzantine period, the controversy is by no means restricted to the clergy, or to arguments from theology.
Iconoclasm seems to have been supported by many from the East of the Empire, and refugees from the provinces taken over by the Muslims.
The continuing cultural confrontation with, and military threat from, Islam probably has a bearing on the attitudes of both sides.
It has been suggested that their strength in the army at the start of the period, and the growing influence of Balkan forces in the army (generally considered to lack strong iconoclast feelings) over the period may have been important factors in both beginning and ending imperial support for iconoclasm.
