From what I can tell the clergy of Al'akbar and the Baklunish people are an obvious take off the islamic world, which have two major divisions in faith (in this case Al'Akbar is the prophet muhammed, and the divisions are The Exalted Faith and the True Faith rather then Suuni or Shia) and the priests are pretty much, the same (and Mullah is even a Real Life title for an islamic priest).
There also seems to be a touch of "grail quest" thrown in, with the followers of Al'Akbar hunting after the Cup and the Talisman, ancient relics of Al'Akbar, as sort of a way to prove their worth (for only the worthy shall find them).