Then what about the muslims that HAVE mixed well with the western world?

No problem with them. Just drop the religion that's the cause of the horror show. If you read the book, you will know. Let me know when you're done. If you come to another country to live a better life, then leave the cause of the worse life behind. Don't bring it with you so others can have a taste of it.

If they can't accept being French (or whatever) then they can leave along the cause of the infection. They may be normal, their children can be normal, but that doesn't change the fact that the religion teaches what the killers execute in their action. Give time and it will start all over again, or at least give space for more religious nut jobs that will protest condoms, vaccines, homosexuals just because it offends their religious beliefs. Hence my "cause further suffering" analogy, but in a social and not biological context (as in the word "pain" doesn't translate well). It's cruel, but unless you get rid of the ideology it will spawn more hate, cruelty and horror given time.

If I may nerd-out for a moment, "the needs of the many outweigh the needs of the few". If you want an organism to be healthy, you have to get rid of the cause of the infection.

To cut them out of western society just because its too tough to let them in is just weak and lacking resolve.

Illogical. It's like saying "making sure you won't catch malaria or ebola is weak and pathetic". Does defending oneself from harm really a sign of weakness?

Of course, we do have an alternative. So then, let's all throw out our meds and let only the strong survive. And that would be the infection as of now. In time an immune organism would show up, but it may be completely different than what we know today and at a cost of the deaths of many "weak" organisms. It could be much crueler than what I propose too.

That's giving up, and it fundamentally alters western culture.

Culture always changes, even fundamentally. Each country is fundamentally different from what we know was 1000, 100 or even 50 years ago. In biological sense, evolution and adaptation helps organisms survive. Those that don't adapt to their surroundings suffer or simply die.