I don't know.
I feel as if those directly involved don't know either.
In Europe there was the hundred years war , about how it was better to be Protestant or better to be Catholic.
As it turns out a Europe that is about half Catholic and half Protestant works just fine, if only they could have figured this out without the war first.
The battle over which sect of Islam is best has been going on for 1400 years give or take a century, there must be a record being set.