Cross : in the New Testament the instrument of crucifixion, and hence used for the crucifixion of Christ itself (Ephesians 2:16; Hebrews 12:2; 1 Corinthians 1:17,18; Galatians 5:11; 6:12,14; Philippians 3:18). The word is also used to denote any severe affliction or trial (Matthew 10:38; 16:24; Mark 8:34; 10:21).
The forms in which the cross is represented are these:
After the conversion, so-called, of Constantine the Great (B.C. 313), the cross first came into use as an emblem of Christianity. He pretended at a critical moment that he saw a flaming cross in the heavens bearing the inscription, "In hoc signo vinces", i.e., By this sign thou shalt conquer, and that on the following night Christ himself appeared and ordered him to take for his standard the sign of this cross. In this form a new standard, called the Labarum, was accordingly made, and borne by the Roman armies. It remained the standard of the Roman army till the downfall of the Western empire. It bore the embroidered monogram of Christ, i.e., the first two Greek letters of his name, X and P (chi and rho), with the Alpha and Omega. (See A.)