Islam is a religion. There is no ambiguity about its origins.
In the media the term "Muslims" is used to characterize people who by definition are not Muslims by their behavior as well as people who have Muslim heritage (family, etc.) but are not active worshipers, and those who are active worshipers but who run the gamut of casual to the intense.
The point of raising this question is the notion that somehow Arab governments and people, as well as African Muslims and Asian Muslims and the few European and North American and Caribbean Muslims, tacitly back the atrocities committed in the name of Islam by a supposed silence. What crockery I say!