The sign of the Cross is one of the most familiar symbols of the Orthodox Christian Faith. This symbol of the Cross expresses two essential elements of the Christian mystery, Christ's victory over death by His death. Through Christ's death, life rose gloriously and triumphantly. The Cross is the symbol par excellence of a God who became flesh and dwelt among us in order to bring salvation to the world. It is the symbol of the Holy Trinity, the One God, Father, Son and Holy Spirit. The symbol of the Cross, in the "fullness of time" became the instrument of redemption and our means to glorification. St. John Chrysostom writes: "I call him King because I see Him crucified: it belongs to the King to die for his subjects."
As early as the second century the sign of the Cross became part of Christian practice. The early Christians would mark their foreheads with the Cross. Tertullian recorded in the second century: "In all our travels and movements, in all our coming in and going out,...whatever employment occupies us, we mark our foreheads with the sign of the Cross." St. Cyril of Jerusalem writes in the fourth century: "Let us not be ashamed to confess the Crucified...let the Cross be our seal, made with boldness by our fingers on our brow and in everything..."
In the East, the Orthodox Church was faced with the heresy of Monophysitism around the time of the sixth century. The Monophysite heresy denied the two natures of Our Lord Jesus Christ as both God and man. The Christians began to more boldly profess the Christian mystery of the Cross. No longer did they just trace the Cross on their foreheads but now more boldly on the body. The ensuing centuries witnessed the formation of the hand to profess more deeply the Holy Trinity, the double natures of Christ our God and the Redemption. The thumb and the two fingers were extended to symbolize the Trinity, while the ring finger and the little finger were folded back on the palm to profess the God-man, Jesus Christ.
By the thirteenth century, the Bishop of Rome, Pope Innocent III, directed most explicitly the the sign of the Cross be made with three fingers, from the forehead to the breast and from the right to the left shoulder. The Church of Rome retained this proper form of the sign of the Cross until the fourteenth century. It was only around that period that the open hand was introduced and the sign of the Cross was made in the inverted way from left to right.
Orthodox Christians sign themselves with the Holy Cross at every mention of the Holy Trinity usually in conjunction with a metany, full body bow or bow of the head. The sign of the Cross is a symbol of faith. St. John of Damascus writes: "For wherever the sign shall be , there also shall He be."
In the Eastern and Western expression of the Orthodox Christian Church we retain the correct practice of the holy Sign of the Cross and encourage the faithful to make it often as a reminder of their life in the Holy Trinity, their profession of faith in the two natures of Christ our God, and as a reminder of the Redemption Christ wrought for us upon the altar of the Cross.