That's not entirely true. In some situations, "Muslim" are an ethnic or national category. What is the difference between Serbs, Croats and Bosniaks? They live in the same place, speak the same language, eat the same food (more or less) and practie different religions. And in China, the Hui are Han Chinese who are Muslims. In the United States, there is a distinction made between "regular" African Americans and the Nation of Islam.
No, it is is not. In any situation, it is a confession, and the fact that in some ethnic or national groups it prevails, does not change anything.
Cut the crap (invented, in the case of former Yugoslavia, by the Comintern stouge Tito).