Never act all mighty and all-knowing with Multi-Kulti and then go on to offend them with predictable consequences. These fundamentalists are never part of your multi-kulti integration anyway, you simply left them out of the picture, and there are only a handful of cultures that can successfully integrate into yours. Either respect their view (which you say contradicts your ideals) or stop that multi-kulti nonsense.
Ever wonder why things escalate this far? Because somebody (ex-neocolonialist, e.g. USA) has chosen to abandon hope, and other country (one particular country) took over its helplessly lost population. This is strongly hinted in entry #1 of this Cracked article:
http://www.cracked.com/blog/4-bizarrely-specific-things-being-taken-over-by-one-country_p2/I can confirm on Indonesia growing radicalism. Yes, people are steadily become more fundamentalist than ever. They tried to shock their way in back in 2001, by actively participating in regional conflicts (e.g. Maluku, East Timor, Aceh, etc). Although regulated and controlled by high-ranking military officials, they have grown out of control by 2003 and committed unspeakable atrocities (e.g. gutting out pregnant women and posting them on internet, yes ISIS is so old). So they were scaled back from semi paramilitary organisation into common fundamentalist gang that regularly raids indecent entertainment centers during fasting months. Their approach softens too, but you can see their efforts slowly ebbing into our daily life, like increasing censorship, historical revision (out traditional clothing got even more complicated to address their modesty standard), and a lot of things that weren't there before 2000s. Once they regard other Muslims from different school of thoughts as infidels, now they see their common faith as the groundwork to slowly steer them into their doctrines. And recently, they reached other ethnics too, I was about to be softly recruited into one of their "sharing sessions." Absurd, but they are getting more courageous.
Where else did this happen? Well, ever heard Pakistan? A country founded for religious reason, yet liberal enough that it elected western-educated party-going female Prime Minister back in 1980s? Ever heard how PIA (Pakistan Intl Airlines) were so globally exist back then? But why are they so secluded now? So fanatic? Because, back in 1990s, when problems in their neighbouring Afghanistan arise, due to escalating civil wars after the Soviet left, nobody helps them, and they turned into that same fookin country to chill Afghan warlords down. Which in turn, turned them from that 1970 religious hippy into what you see today.
What happens with China and India? Well, they deal with it the hardest way. But it is also because they were never part of US communism paranoia during cold war era. It seems to me, that slow, under-the-blanket radicalisation only happen in countries so lost after being abandoned by US and its allies. We were lost after 1997 crisis, and the Pakistan were lost after they can't beat Soviet-friendly India.
And no, it is not a good idea to keep flailing genitals and obscenities at them. It is not a progress, it is decadence. Like it or not, you gotta take the Saud King's approach on things with them: give and take. That's why they can enjoy Ferrari and Rolex while beheading witches. Now, what would you give for something that is absolutely not trade-able?
Another way is to take charge, take control of the school of thoughts, like Indonesia did. "Officially, we believe in this version of Islam, and yours is just yours!" This way, you'll offend only certain groups, since you take firm stance on one specific discipline. The majority will rally behind the stronger and the one with more popular support. This will isolate those fundamentalists and make them stick out like sore thumb.
Lastly, the cost of freedom is always high. Yes, indeed.
