The Chi-Rho symbol (☧) combines two Greek letters into a symbol that looks like the letter X placed over the stem of the letter P. The Greek letters chi and rho are found at the beginning of Χριστῷ, which translates to “Christ” in English. The Chi-Rho is also called the Christogram because it is a monogram of Christ. This symbol gained popularity representing the name of Christ during the time of Constantine in the fourth century AD.
The historian Eusebius tells of Constantine’s use of the symbol, describing how Constantine sought military victory over Maxentius and began to look to different gods to help him (Life of Constantine, I. 27). Since Constantine realized that those who followed multiple gods were usually defeated, “he felt bound to honor his father’s God alone” to ensure victory just as his father had done (I. 27). It is unclear whether Constantine’s father was a Christian, although this has become a popular view over time. One day, Constantine is said to have had a vision of the cross in the sky with the inscription that read, “By this symbol you will conquer” (I. 28). Later, Constantine was uncertain about the vision and supposedly had a dream in which Christ instructed him to use the symbol he had seen as protection in battle. The next day, Constantine had a banner containing the sign made; atop the cross-shaped pole, in a golden wreath, was the Chi-Rho. This standard, also used by later Christian emperors, was called the Labarum. The Latin church father Lactantius, who was also an advisor to Constantine, wrote of how the Chi-Rho was placed on the soldiers’ shields for protection (“On the Deaths of the Persecutors,” 44.5). Constantine’s army was victorious against Maxentius, and Constantine continued to use the Chi-Rho symbol prominently, even having it engraved on his armor and helmet, according to Eusebius.
There is no mention of the Chi-Rho symbol in the Bible. The Greek letters chi and rho are used to make up the name Christ in Greek, but the symbol is not mentioned. That hasn’t stopped the Chi-Rho from being used on banners, clerical stoles, chasubles, cruets, candle stands, rings, cufflinks, watches, hats, shirts, coffee mugs—just about anything. In Christian paintings and engravings the Chi-Rho is often depicted with the Greek letters alpha (Α) and omega (Ω) on either side, representing Jesus Christ as the Alpha and Omega (see Revelation 1:8; 22:13).
The Chi-Rho symbol has been used for centuries to acknowledge Christ. It has also been used, since its very conception, as a good-luck charm to ward off disaster. Of course, there is nothing wrong with reminders of Christ, but any use of the Chi-Rho as a talisman, amulet, or charm crosses the line into superstition and should be rejected.