Q: I’ve wondered about this ever since I was a schoolchild many years ago: When did we start pronouncing “Christ” with a long “i”?
A: In Old English and Middle English, the name was Crist (“the anointed one”); the “ch” spelling didn’t become standard until after 1500, according to the Chambers Dictionary of Etymology.
The word is an Anglicization of the Greek title Kristos (Latin Christus), meaning “anointed.” In the classical languages, the first vowel had a short “i” sound (as in “mist”).
The name was pronounced with a short “i” in Old English too – until Irish missionaries in England in the 600s and 700s encouraged the long “i” pronunciation (as in “heist”).
I haven’t been able to find out why the missionaries did this. However, the derivatives “Christian,” “Christmas,” and all the rest kept the short “i.”
German, by the way, retains the old short-“i” pronunciation. The name Kriss Kringle comes from the German Christkindl (German for “Christ child”). In German, “Christ” sounds like “Kriss” with a “t” at the end.