Crucifix

Since by His holy sacrificial death upon the Cross Christ sanctified this former instrument of shame and ignominy, it must have very soon become in the eyes of the faithful a sacred symbol of the Passion, consequently a sign of protection and defence (St. Paulinus of Nola, "Carm. in Natal. S. Felicis", XI, 612; Prudent., "Adv. Symm.", I, 486). It is not, therefore, altogether strange or inconceivable that, from the beginning of the new religion, the cross should have appeared in Christian homes as an object of religious veneration, although no such monument of the earliest Christian art has been preserved. Early in the third century Clement of Alexandria ("Strom.", VI, in P. G., IX, 305) speaks of the Cross as tou Kyriakou semeiou typon, i.e. signum Christi, "the symbol of the Lord" (St. Augustine, Tract. cxvii, "In Joan."; De Rossi, "Bull. d'arch. crist", 1863, 35, and "De titulis christianis Carthaginiensibus" in Pitra, "Spicilegium Solesmense", IV, 503). The cross, therefore, appears at an early date as an element of the liturgical life of the faithful, and to such an extent that in the first half of the third century Tertullian could publicly designate the Christian body as "crucis religiosi", i.e. devotees of the Cross (Apol., c. xvi, P. G., I, 365-66). St. Gregory of Tours tells us (De Miraculis S. Martini, I, 80) that in his time Christians habitually had recourse to the sign of the cross. St. Augustine says that by the sign of the cross and the invocation of the Name of Jesus all things are sanctified and consecrated to God. In the earliest Christian life, as can be seen from the metaphorical language of the primitive faithful, the cross was the symbol of the principal Christian virtue, i.e. mortification or victory over the passions, and suffering for Christ's sake and in union with Him (Matt., x, 38; xvi, 24; Mark, viii, 34; Luke, ix, 23; xiv, 27; Gal., ii, 19; vi, 12, 14; v, 24). In the Epistles of St. Paul the cross is synonymous with the Passion of Christ (Ephes., ii, 16; Heb., xii, 2) even with the Gospel, and with religion itself (I Cor., i, 18; Phil., iii, 18). Very soon the sign of the cross was the sign of the Christian. It is, moreover, very probable that reference to this sign is made in the Apocalypse (vii, 2): "And I saw another angel ascending from the rising of the sun, having the sign of the living God."
It is from this original Christian worship of the cross that arose the custom of making on one's forehead the sign of the cross. Tertullian says: "Frontem crucis signaculo terimus" (De Cor. mil. iii), i.e. "We Christians wear out our foreheads with the sign of the cross." The practice was so general about the year 200, according to the same writer, that the Christians of his time were wont to sign themselves with the cross before undertaking any action. He says that it is not commanded in Holy Scripture, but is a matter of Christian tradition, like certain other practices that are confirmed by long usage and the spirit of faith in which they are kept. A certain Scriptural authority for the sign of the cross has been sought by some in a few texts rather freely interpreted, especially in the above-mentioned words of Ezechiel (ix, 4), "Mark Thau upon the foreheads of the men that sigh, and mourn for all the abominations that are committed in the midst thereof", also in several expressions of the Apocalypse (vii, 3; ix, 4; xiv, 1). It would seem that in very early Christian times the sign of the cross was made with the thumb of the right hand (St. John Chrys., Hom. ad pop. Antioch. xi; St. Jerome, Ep. ad Eustochium; a practice still in use among the faithful during Mass, e.g. at the reading of the Gospel) and generally on the forehead; gradually, by reason of its symbolism, this sign was made on other parts of the body, with particularized intention (St. Ambrose, De Isaac et animâ, Migne, P. L., XIV, 501-34). Afterwards these different signs of the cross were united in one large sign such as we now make. In the Western Church the hand was carried from the left to the right shoulder; in the Eastern Church, on the contrary, it was brought from the right shoulder to the left, the sign being made with three fingers. This apparently slight difference was one of the (remote) causes of the fatal Eastern Schism.