The Chi-Rho Cross is composed of the Greek letters Chi (which looks like an English "X" and sounds like a "ch") and Rho (which looks like an English capital "P" and sounds like an "r"). These two Greek letters are the first two letters in the Greek word "Christos," translated in English as "Christ." This symbol has been in use for at least 1,600 years.

While fighting to become emperor of the Roman Empire, Constantine had a dream one night before a battle with Maxentius and his forces. In the dream Constantine saw the Chi-Rho cross and saw the words "By this sign you will conquer." Upon awakening, Constantine had the symbol put on his helmet and on his soldiers' shields. The next day, October 28, 312, Constantine was victorious in battle. He attributed his success to God and began to favor the Christian church after many years of the church being barely tolerated or persecuted by the Roman Empire. Obviously the Chi-Rho cross which had existed before Constantine's time took on a new meaning for Christians after this event.