There may be three separate things to consider: -

1. What the Koran (and other accepted Islamic works) say.
2. What some apparent Muslims say and do in the name of thier religion
3. What some allegedly (or nominally) Islamic states so say and do.

The point is familiar in that right wing idealogues used to produce a catalogue of wrongs they stated were committed by communist states - but failed to see that a state might call itself communist but not truly reflect communism.