Throughout history, a number of symbols have been used in Christianity to represent aspects of the life and teachings of Jesus Christ as well as the Christian Church. In the early years of the growth of the church, it was dangerous for Christians to practice their faith in public because they were persecuted by the Roman Empire. As a result, certain symbols arose to secretly convey the teachings of Jesus without raising the notice of Roman authorities. Among these symbols were the so-called nomina sacra (meaning "sacred names"), which were abbreviations of divine names/titles used in early Greek scripture. Terms of reverence for Christ such as Lord, Son, Spirit, Savior, and so on, were written with overlines to indicate their special importance for the early Christians. Starting in the third century the nomina sacra were sometimes shortened by contraction in Christian inscriptions, resulting in sequences of Greek letters such as IH (iota-eta), IC (iota-sigma), or IHC (iota-eta-sigma) for Jesus (Greek Iēsous), and XC (chi-sigma), XP (chi-ro), and XPC (chi-rho-sigma) for Christ (Greek Christos). Here "C" represents the medieval "lunate" form of Greek sigma; sigma could also be transcribed into the Latin alphabet by sound, giving IHS and XPS. One of the oldest Christian symbols is the Chi-Rho or Labarum. It consists of the superimposed Greek letters Chi Χ; and Rho Ρ, which are the first two letters of christ in Greek. Technically, the word labarum is Latin for a standard with a little flag hanging on it, used in the army. A Christogram was added to the flag as an image of the Greek letters Chi Rho, in the late Roman period.
In the Latin-speaking Christianity of medieval Western Europe (and so among Catholics and many Protestants today), the most common Christogram is "IHS" or "IHC," derived from the first three letters of the Greek name of Jesus, iota-eta-sigma or ΙΗΣ. Here the Greek letter eta was transliterated as the letter H in the Latin-speaking West (Greek eta and Latin-alphabet H had the same visual appearance and shared a common historical origin), while the Greek letter sigma was either transliterated as the Latin letter C (due to the visually-similar form of the lunate sigma), or as Latin S (since these letters of the two alphabets wrote the same sound). Because the Latin-alphabet letters I and J were not systematically distinguished until the seventeenth century, "JHS" and "JHC" are equivalent to "IHS" and "IHC."
"IHS" is sometimes interpreted as meaning Iesus Hominum Salvator ("Jesus, Savior of men," in Latin), or connected with In Hoc Signo. Some uses have even been created for the English language, where "IHS" is interpreted as an abbreviation of "I Have Suffered" or "In His Service." Such interpretations are known as backronyms. Its use in the West originated with St. Bernardine of Siena, a 13th Century priest who popularized the use of the three letters on the background of a blazing sun to displace both popular pagan symbols and seals of political factions like the Guelphs and Ghibellines in public spaces.
Many Eastern Orthodox Churches use the Greek letters INBI based on the Greek version of the inscription, Ἰησοῦς ὁ Ναζωραῖος ὁ Bασιλεὺς τῶν Ἰουδαίων. Some representations change the title to "ΙΝΒΚ" ὁ Bασιλεὺς τοῦ κόσμου ("The King of the World"), or "ΙΝΒΔ" ὁ Bασιλεὺς τῆς Δόξης ("The King of Glory"), not implying that this was really what was written, but reflecting the tradition that icons depict the spiritual reality rather than the physical reality. Some other Orthodox Churches (such as the Romanian Orthodox Church) use the Latin version INRI. The Russian Orthodox Church uses ІНЦІ (the Church Slavonic equivalent of INBI) or the abbreviation Цръ Слвы ("King of Glory").
In Hebrew, the phrase is commonly rendered ישוע הנצרי ומלך היהודים (Yeshua' HaNotsri U'Melech HaYehudim IPA: jeːʃuːɑʕ hɑnːɑtseri meleχ hɑjːəhuðiːm), which translates instead to "Jesus the Nazarite and King of the Jews." This version was most probably chosen in order that the acronym constitute the tetragrammaton (יהוה) name corresponding with Yahweh or Jehovah. It is possible that the titulus was written in Aramaic, the local vernacular, rather than Hebrew.
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