This, they are saying "we are muslims" but they do not know what is the meaning of "Islam".
You can't run away by saying something like this.
The ISIS has support only from Muslims, and their plan is the complete extermination of all non-Muslims. And contrary to the popular myths, there is a lot of support for ISIS among the Muslims. Moreover, they are supported by Saudi Arabia, which is the decision taker for the Sunni Muslims around the world.
This is not mean they are real *muslims, or am I wrong? *When they will kill also muslim people, and christians etc... They are also supported by Saudi Arabia, but also other nations (and this is obviously not public). However you are (maybe) right, I cannot say (simple) that they are not muslims but all their action does not represent a real muslim.