I've talked to a number of Christians over the years who were surprised to learn that the New Testament was not originally written in Hebrew, but in Greek. This blows their mind, because people associate the Christian Bible's original language with Hebrew. This is understandable, because most of the Christian Bible really was written in Hebrew - the Old Testament (or "Hebrew Bible," if you prefer) was written almost exclusively in Hebrew - all but about 250 verses of it, which were originally written in Aramaic. Besides Hebrew and Greek, there is one other language for Christian scholars, who want to read the Christian Bible in the original. (And you thought your mind wasn't blown enough ... )
I can guess what most of you are probably thinking: "What the heck is Aramaic, and why did the authors of the Bible choose to write in it?" If the ancestral language of the Jews was Hebrew (and it was), why did the Jewish authors of what we today call the "Old Testament" not write everything in Hebrew?
Map of the Ancient Near East