I guess I missed the part in my history class where Baptists and Methodists killed each other for centuries over their differences. A better analogy would be Catholic/Protestant who actually did do that. But Islam is still stuck in the 16th century in that regard (if not the 7th century).
I guess I’m saying they have much more in common with each other than with any of us. So if we attack them - they will tend to stand with each other. Against us.