Underlying unrest and conflict in Syria and elsewhere in the Middle East is sectarian divide. In Syria, Alawites, a Shia sub-sect, rule over a population that’s 70 percent Sunni. Sunni-run Qatar and Saudi Arabia supply weapons to Syrian rebels, mostly Sunni, even while hoping to keep their own sizable Shia populations at bay. War in Syria poses regional dangers, and in the second article of a two...