For more than three hundred years after the first publication of the gospel there is good reason to believe, that neither images nor any other visible objects of religious reverence were admitted into the public service of the churches, or adopted into the exercises of private devotion. Probably such a thing had never been thought of by Christians before the days of Constantine; and we can only regard it as an early fruit of the union of Church and State. Up till this period the great protest of Christians was against the idolatry of the heathen: for this they suffered unto death. And it is not a little remarkable, that the Empress Helena, Constantine's mother, was the first to excite the christian mind to this degrading superstition. She is said, in her zeal for religious places, to have discovered and disinterred the wood of the "true cross." This was enough for the enemy's purpose. The predilection of human nature for objects of veneration was kindled; the flame spread rapidly; and the usual consequence—idolatry—followed.
Similar memorials of the Savior, the Virgin Mary, the inspired Apostles, and the Fathers, were found. The most sacred relics that had been concealed for centuries were now discovered by visions. So great, so successful, was the delusion of the enemy, that the whole church fell into the snare. From the age of Constantine till the epoch of the Arab invasion, a veneration for images, pictures and relics gradually increased. The reverence for relics was more characteristic of the Western, and that for images of the Eastern churches; but from the time of Gregory the Great the feeling of the West became more favorable to images. In consequence of the almost total decay of literature, both among the clergy and the laity, the use of images was found to give immense power to the priesthood. Pictures, statues, and visible representations of sacred objects became the readiest mode of conveying instruction, encouraging devotion, and strengthening religious sentiments in the minds of the people. The more intellectual or enlightened of the clergy might endeavor to maintain the distinction between respect for images as a means and not as objects of worship. But the undiscriminating devotion of the vulgar utterly disregards these subtleties. The apologist may draw fine distinctions between images as objects of reverence and as objects of adoration; but there can be no doubt that with ignorant and superstitious minds the use, the reverence, the worship of images, whether in pictures or statues, invariably degenerates into idolatry.
Before the close of the sixth century idolatry was firmly established in the Eastern church, and during the seventh century it made a gradual and very general progress in the West, where it had previously gained some footing. It became usual to fall down before images, to pray to them, to kiss them, to adorn them with gems and precious metals, to lay the hand on them in swearing, and even to employ them as sponsors at baptism.