When we make the sign of the cross, we touch with the two fingers of the right hand — the index and the middle finger — upon the forehead, the navel, the right shoulder and the left shoulder. The index and the second (middle) finger are stretched out and joined, the second finger a bit tilted. These two fingers represent the two natures of Christ, our Lord: divine and human. By crossing in such wise, we bear evidence that Jesus Christ is both the true God and a true (perfect) Man. The second, inclined, finger symbolizes that God assumed the similitude of His creation and descended to Earth to accomplish our salvation. The remaining fingers of the right hand: the thumb, the ring and the little finger are joined in testimony of our profession of the One Tripartite God, the Holy Trinity: the Father, the Son and the Holy Spirit.
In so making the sign of the cross — the symbol of the crucified God — on our body, we first touch the two fingers on the forehead, thus signifying that Christ is our true Head. Then we apply them to the belly (or, heart); thus doing, we confess that God had come down from Heaven and had been immaculately fathered in the pure womb of His Virgin Mother. By touching the right shoulder with our fingers, we confess that, upon His ascension, Christ had sited solemnly to the right of His Father. And, by touching the left shoulder we recall the second glorious Coming of the Son of God and the Day of Judgment, when sinners will align at the left hand of God.
The sign of the Cross should always be accomplished with particular piety, in a proper and zealous way. Our body should feel the touch of our fingers. It is important not to hurry when making the sign of the cross; you must not begin to bow before finishing crossing yourself. The writ (patristic canon) calls such a negligently executed sign of the cross “arm brandishing in which demons rejoice.” We must always bear in mind that by accomplishing the sign of cross consciously and properly we acknowledge the principal articles of the true Christian faith.