By their own definition, they are infidels. Just think of how the 9/11 hijackers assimilated into American society before their "big day". Just read their "handbook". I suggest you also read Stephen Emerson's book. He has a map of where all the cells are located in the U.S. I don't think they broadcast their intentions on the radio or on the street corner.
So they are infidels...they are still Muslims...just as there are many different Christians, Jews, etc. I believe,
we are fighting individuals, not a religion.