My @Quora answer to Why can't Muslims take criticism of Islam?
Answer by Jim Ashby:
Because Islam is based on the clear, perfect, immutable, inerrant, word of Allah: The Quran. As the foundation of Islam, the Quran is inviolable . . . not just by Muslims but, rather, by non-Muslims too: by everybody.
Unlike the Bible, with its stories and parables and symbolism, the Quran was not authored by men: it was authored by Allah himself. It's straight-up preaching from beginning to end. As such, not a single word of it may be challenged. Mortal men are simply insignificant in comparison to Allah.
Additionally, the Quran is unrelentingly, self-reinforcingly, fundamentalist. It repeatedly exhorts believers to keep believing and condemns non-believers, unbelievers, disbelievers, misbelievers and ex-believers for not believing. It repeatedly cautions believers to be wary of non-believers and not trust them. It repeatedly tells believers they will not be believed and that Allah knows best.
Try to imagine religious indoctrination to such totalitarian and supremacist teachings. Now toss in a healthy dose of xenophobia and militarism: the evil of infidels and the glory of holy war (jihad). Islam is not merely a 'religious sphere of influence': it encompasses all of life. There is no secular realm or component: not even in politics or law. So when you disrespect Allah, Islam, the Quran or Muhammad, you disrespect the entire ummah of Islam. It's no different, to Muslims, than a personal attack that warrants self-defense. Such disrespect is all the warrant needed for violent retaliation. Cartoon of Muhammad, anyone?
That's how totalitarianism and supremacism turn tolerance on its head. Non-Muslims must respect Islam. It's not negotiable. And therein lies fertile grounds to license violence. As of 2011, worldwide statistics reveal that 70% of terrorist killings were perpetrated by Sunni Muslims — who comprise about 85% of all Muslims. If you take an average estimate of 1.6 billion Muslims in the world, then 85% of that equals 1.36 billion Sunnis. This represents 19.43% of the world's 7 billion people. So terrorists among that 19.43% of the world's population commits 70% of the world's terrorist killings, year after year. All else being equal, that's 3.6 times higher than what should be expected . . . yet apologists would have us believe it has nothing to do with Islam.
“I am treated as evil by people who claim that they are being oppressed because they are not allowed to force me to practice what they do.” ~D. Dale Gulledge