The Emperor Leo III., surnamed Isauricus, a prince of great abilities, had the boldness to undertake, in the face of so many difficulties, to purify the church of its detestable idols. As the writings of the unsuccessful party were carefully suppressed or destroyed, history is silent as to the Emperor's motives: but we are disposed to believe that the new creed and the success of Mahomet greatly influenced Leo. Besides, there was a very general feeling among Christians in the East, that it was the increasing idolatry of the church that had brought down upon them the chastisement of God by the Mahometan invasion. The Christians were constantly hearing from both Jews and Mahometans the odious name of idolaters. The great controversy evidently arose out of these circumstances.
Leo ascended the throne of the East in the year 717; and, after securing the empire against foreign enemies, he began to concern himself with the affairs of religion. He vainly thought that he could change and improve the religion of his subjects by his own imperial command. About the year 726 he issued an edict against the superstitious use of images -not their destruction. We cannot suppose that the Isaurian was actuated by the fear of the true God in this, but rather that his motives were purely selfish. Being head of the empire and still ostensibly head of the church, he no doubt thought that by his edicts he could accomplish the total and simultaneous abolition of idolatry throughout the empire, and establish an ecclesiastical autocracy. But Leo had greatly overrated his temporal power in spiritual matters. The time was past for imperial edicts to change the religion of the empire. He had yet to learn, to his deep mortification, the disdainful, insolent, haughty pride and power of the pontiffs, and the religious attachment of the people to their images.
The first edict merely interdicted the worship of images, and commanded them to be removed to such a height that they could not be touched or kissed. But the moment that the impious hand of the Emperor touched the idols, the excitement was immense and universal. The proscription affected all classes: learned and unlearned, priest and peasant, monk and soldier, clergyman and layman, men, women, and even children, were involved in this new agitation. The effect of the edict immediately occasioned a civil war both in the East and in the West. The monkish influence was especially strong. They set up a pretender to the throne, armed the multitude, and appeared in an ill-equipped fleet before Constantinople. But the Greek fire discomfited the disorderly assailants; the leaders were taken and put to death. Leo, provoked by the resistance which his edict had met with, issued a second and more stringent decree. He now commanded the destruction of all images, and the whitewashing of walls on which such things had been painted.