The only thing I could add is from the individual point of view. In the end-of-the-world Protestant heresies it is important to note that when the end of the world does not occur, proselytizing increases rather than decreases and another date is set.
Uncertainty of faith is a common experience. Some look for external reinforcement in the physical world. Others redouble efforts and deny their doubts by become super religious with an unquestioning mind.
Some seek to prove their faith with vehemence--I think this is the way some Muslims react. Rather than face their doubts they attack the source of their doubts. Others facing doubt and despair engendered thereof are eager to die as jihadists or suicide bombers. Again, proving their faith,denying their doubts and ending their uncertainty with suicide.
I do believe the Muslims are facing a crisis of doubt and uncertainty. Soon this will crumble under as the individual doubters become the movers and shakers. In the meantime they and we suffer.
Never underestimate the need for an individual to find certainty where none exists. Out of this goal or need much evil occurs.
Your post (#53) makes a lot of sense.