The veneration of saints and relics took its rise on the overthrow of paganism at the time of Constantine. It was very natural that those who had suffered martyrdom at the hands of pagan persecutors should at that time be remembered; and so it came to pass that churches were considered honoured above all others which contained the relics of those martyrs. The bones of Christ's witnesses were removed from their lonely graves, where they had lain long neglected, and were deposited under Christian altars. Saint's days were appointed upon which their deeds were rehearsed and their lives commemorated. From a veneration of the saints it was a short step to their invocation, and what helped the Church to take that step was the difficulty felt by men in regarding Jesus Christ as being at once God, and the Mediator between God and man.
The chief of saints is the Mother of our Lord after the flesh. The title applied to her -- Mother of God -- is quite intelligible, when we recollect the strife of the Arian controversy, and the determination of the Church to maintain the eternity of the Son and His equality with God.
Saint worship is not countenanced: saints are venerated and invoked, but not worshipped. Ignorant people in the East, even as is the case with ignorant and superstitious people in the West, in all Churches, fall into divers errors; but the invocation of the saints is quite intelligible to the ordinarily instructed minds in the Church, and in their view in no way robs the Three One God of the worship and glory that are due to Him alone.
There are no images in Eastern churches. The onslaught of the iconoclasts of the ninth century stripped Eastern worship of much that beautified and embellished it, but icons, or sacred pictures remained, and are held in as profound veneration, as is the image of any saint in the Church of the West. The icons are very varied in their representations. They represent our Lord and Joseph and Mary; the apostles, saints, and martyrs; and some of them depict interesting incidents from the scriptures. Prayers are said before them, that a devotional spirit may be aroused and sustained by the scene depicted. In the commoner churches those icons are in many cases miserable daubs, but in some of the larger and wealthier churches, and in many of the older buildings where they are executed in mosaic, they are often works of the highest art.
Unlike the Roman Church, the Greek Church claims no infallibility. Works of supererogation are not allowed, and there are consequently no grants of indulgence or dispensations. The state of the dead is final -- the souls of the departed passing at once into a state of bliss or torment. Purgatory therefore is disallowed, and prayers for the dead are but a pious custom, by which the memory of the departed is kept fresh.