Problem is culture not religion. If it was strictly religion, we wouldn't have islamic politications, immigrants, etc in America now who get along just fine. The problem comes when you bring over whackos fresh from their home country who are used to doing 16th century shit.
Christiany in the US has only gotten over it relatively recently by largely forcing the powerful groups into their own privately owned camps, cults, and mega churches. Freedom of speech being woven into the law also helped a great deal as well.
Law manipulation is another way we don't notice their influence such as circumcision. A procedure that is largely unneeded in males, has a both rate that includes permanent dysfunction of the penis, and min. advantages. Yet this is banned to females.
You want to fix the crazies, integrate and force cultural exchange. The melting pot is how you separate those who truly want to start a new leaf from the nuts. Plus you get to learn something new.