What power has the sign of the cross, used on this and other occasions?

The sign of the cross, made with faith by the motion of the hand or represented in any other way, is like the utterance of the name of Jesus: “there is salvation in no one else, and there is no other Name under heaven that is given among mortals by which we should be saved” (Act 4:12; see Q130, Q484).

Not only is the Name Jesus (“YHWH saves”) of unique significance, but so is the very sign of the cross, in which the Apostle glories: “But as for me, I shall find glory in nothing, except in the cross of our Lord Jesus Christ, through which the world has been crucified to me, and I to the world” (Gal 6:14; see Q008, Q208).

St Cyprian echoes the universal belief of the early Christians: “in this sign of the cross there is salvation for all who are marked on their foreheads” (St Cyprian of Carthage, on the mark of Ezk 9:4; see Q299, Q307). St Cyril of Jerusalem exhorts the catechumens:

Let us not be ashamed to confess the Crucified. Let us boldly make the sign of the Cross on the forehead and on everything: on the bread we eat, on the cups from which we drink; at our going out and coming in; when we lie down to sleep and when we rise; when we journey and when we rest. It is a great safeguard, given to the poor without price, to the weak without labor; for this is the grace of God: a token for the faithful, and a terror for evil spirits. (St Cyril of Jerusalem, Catechetical Lectures, 13.36)

In the cross of the King of Glory, the wisdom and victory of God are revealed: the greatest evil has become the greatest good, for all things are “according to the purpose of him who works all things after the counsel of his will” (Eph 1:11; see Q383). As Joseph said to the brothers who had sold him: “you meant evil against me, but God meant it for good” (Gen 50:20; see Q124, Q431). The crucifixion of the Son of God, which the devil intended for evil, has revealed “the depth of the riches both of the wisdom and knowledge of God! How unsearchable are his judgments, and how unfathomable are his ways!” (Rom 11:33; see Q087).