By the same token, a devout Muslim taking up residence in a predominately Christian country will not change his religion. He will always consider Christians or other religious sects as infidels, deserving annihilation.
Many less radical Muslims will not overtly attempt destruction, but the more fanatic will take the destructive approach toward opposing members of other religions.
Many Muslims assimilate themselves into the general society except for their religious beliefs, but a few radicals do not.
This latter attitude is demonstrated in the recent carnage in Paris (and other areas). Muslims are not seeking to enter a country to reap religious freedom even though that freedom permits them to prosper there. Radicals want to bring others into conformity with their own beliefs while reaping the benefits of freedom.