I think that it's very silly to say that these people aren't Muslims. There is a very old tradition of Muslims destroying what they regard as idols, beginning with Mohammed himself! In Islam,
shirk is the only crime that God cannot forgive.
Shirk is the worship or deification of anything other than God. There is an urge in any religion to see other religions as worthless and dangerous. And so there should be! After all, those religions are
wrong!
Islam has been hijacked by Saudi Wahabis the same way that zionism has hijacked Judaism.