Know thy self, know thy enemy. A thousand battles, a thousand victories.
In the spirit of taking problems by the throat and trying to solve them I've spent several hours today trying to just understand what this flap is all about.
So in that spirit, I offer the following link and initial mindmap. A model.
A model is a characterization of a phenomenon.
It is helpful to the extent that it highlights the principal elements of the phenomenon and their relationships.
It is not helpful in the extent to which it over-simplifies complex relationships.
I offer this model in the spirit of the former, with no intent of presenting the latter. I reserve the right to update this. It derives from
http://www.cfr.org/peace-conflict-and-human-rights/sunni-shia-divide/p33176#!/?cid=otr-marketing_url-sunni_shia_infoguide
It is complicated, you shall not assimilate it in a single afternoon.
But it is a good place to start.