Not sure that really makes the point you think you're making.

The fact that these people were citizens or became citizens perfectly legally doesn't change the fact they all murdered innocent people, did it overtly in the name of their religion, and did so DESPITE years of living in a modern western democracy or even having been born here. There's clearly an issue here with radicalization within that community that we don't see with Sikhism, Buddhism, Shintoism or Hinduism, but we most definitely DO see with Islam.

Why does that community see this radicalization far more often than other immigrant communities? Why is it so tenacious that it survives years of inculcation into western society? 

Your post just moves the point of inquiry down a notch. Clearly, citizenship is meaningless, and it's really who is educating, forming and instructing these people, regardless of citizenship, that's the problem.