Isn’t it incredible how the Bible says the mark will be IN the forehead. But 2000 years ago, who would have thought of a mark being anything other than ON the forehead
Actually, the Greek text says that the mark will be "epi to metwpon autwn" - and "epi" is Greek for "on" or "upon" not "in" as "inside" or "within" in modern English.
In the 1600s when the King James Bible was translated the word "in" had a slightly different sense to it. It could also mean "up to."
In Middle English the word "in" and the word "inne" were two different words with "inne" meaning within or inside something. However, when the final "e" of words like "inne" stopped being pronounced, the distinction was lost.