Chi Rho – The Divine Symbol revealed to Constantine, and also found on the bronze ring at Kourion.
The Greek letters X (Ch) + P (R) are the first two letters of the Greek word ΧΡΙΣΤΟΣ pronounced ‘Christos’.
These initials are known an “The Monogram of Christ” CHR = XP.
For those who are not familiar with the Greek Alphabet, perhaps this explanation will be helpful.
The Greek letter X = Ch and the letter P = R (The letter that looks like a P in English is a Greek R.) In English the monogram would read CHR, and in Greek it would be written as XP and pronounced /Chi-Rho/
This symbol is composed of the P superimposed on top of the X.