No, Dave. You wrote: "The words Zeus and Deus are interchangeable in Greek I think." (My italics.This is false because the word "deus" does not exist in Greek, and the "dios" in the sign means "simply of Zeus" as a particular diety and not "of god," which dei (the genitive of deus) would mean in Latin. "Deus" in Latin and "Zeus" in Greek are related but they do not mean the same thing -- one is particular and one is generic -- and one is not a substitute in Greek (or in Latin, for that matter) for the other as you suggested.

Lee