Regarding Iraq, pundits and political leaders in the U.S. have been quick to point out how the interests of Iraqis would be better served if the members of religious sects would think of themselves as Iraqis first. They have failed to justify that position, and failed to discuss how their logic might apply to religions and nations in the rest of the world.
Unless there is some clear advantage bestowed by a set of shared cultural attributes in the context of the largest environment it is likely to operate, it makes no sense to favor it. Among the most important advantages are health and wealth, which can be measured in terms of life expectancy, infant survival, and gross domestic product (GDP) per capita.
Looking at the Middle East’s distribution of religions, which represent the main divisions within Iraq today, Iraq sits between two concentrations of Islamic sects. Sunnites dominate the region almost everywhere except Iran, where Shi‘a are concentrated. On a nation-by-nation per capita basis, for Iraq’s neighbors (with the exception of Turkey and Yemen), there is a considerable economic advantage, but no health advantage, to being Shi‘a rather than Sunnite. While this fact may be an accident of history, it is no less real, and will no doubt influence the internal pressures determining whether a unified nation would prefer to be Sunnite dominated or Shi’ah dominated.
In terms of influence (advantage multiplied by population), Sunnites dominate Shi‘a among Iraq’s neighbors. To the extent that the neighbors can affect the outcome of the current conflict, all things being equal, the Sunnites would have the advantage by at least a two-to-one margin, with the biggest players being Turkey (for the Sunnites) and Iran (for the Shi‘a). My understanding is that political considerations rule out Turkey, so Saudi Arabia would be a stand-in for the Sunnites (followed closely by Egypt).
These purely demographic considerations seem, at least on the surface, to reflect current events. As I write, Iran has been implicated in training Shi‘a militia, and Saudi Arabia has made noises that it will take an active role in Iraq if the U.S. leaves prematurely.
Regarding the corresponding lessons for the world at large, it might be useful to compare these and other groups in a similar analysis; of course, we would be talking about internal struggle, since the world has no neighbors that we know about. (As far as the Sunnites and Shi‘a are concerned, they are about seven percent of the world’s population, a small but not insignificant number.)