Yes, common enemies can unite people. However, you have to reconcile that with the fact that we haven’t had a lot of problems with the Muslims raised in the US.
There have been several Al-Qaeda sympathizing terrorist cells of U.S. born jihadis busted and prosecuted. One cell was outside of Buffalo, New York... another cell was in Northern Virginia... and there were more.
Until recently almost all Arab immigrants were Christians, and almost all Persian immigrants and Muslim immigrants were not fundamentalists. But if your a fundamentalist Muslim whether Shiite or Sunni, Arab or Persians, you are taught that Infidels are the common enemy.
And then there are the Muslims of CAIR and other front groups, fighting the Jihad by other means - for now!