Sometimes the ignorance and self righteousness of the people go to unprecented levels.
Dear posters, at the time when your PARENTS were born (in 1950ies) Europe was just out of the war, cities and industries were bombed and in ruins. There was good motivation in leaders of these countries to bring their land up and on the top. There was a lot of work to be done and not enough workforce because of WW II casualties. The wages sky rocketed and goods became too expensive to be sold. Then someone had a bright idea "Why don't we get cheap workforce from nearby countries, use them like slaves and built our mighty civilization quickly and send them back to their countries like used handkerchiefs". So the OFFICIAL immigration began, trains load of workers were sent to the factory cities of the Europe. "Gastarbeiters" they were called in Germany. "Guest workers". Arbeit did not make them free, only made their German Employees rich. Because they were guests they were not given any motivation to integrate, no one cared if they learned German or French. They better stayed together in their crowded apartments out of sights. This was how it all began. A first generation measured in hundreds of thousands lived in their limboland, a Turk whose timeline froze in 1950 who was alienated to his own society by every passing year, never accepted by Germans as an equal, just a passer-by, someone to be exploited. His sons and daughters, second and third generations lived the hell on earth, facing an antiquated version of their parents national values and a society who never accepted them. Some chose to decline their heritage and try to adapt, never suceeded while others were easy prey for fundamentalism as a self defense for their "percieved" enemy.
It is now the 5-6th generations, this story became complicated with illegal immigrants, asylum seekers, growing tensions with rising racism, but nevertheless they are not the aggresors who parachuted to your backyards or streets overnight. Europe called them for self interest and now calling them the enemy.
My advice for handling this problem : Give them what they want :They want Sharia-Law for those who would accept it ? Give them, let the fanatics cut a few hands and see who would follow them, marginalize the pricks by exposing their true face to those who are in their vicinity. Protect anyone who chooses to leave the sect. Sometimes dreams are very powerful and seems to unite people for a good/bad cause, show them that theirs is actually a nightmare (maybe it is not). Don't make theşr dream more valuable by denying it.