Show me where in the Quran it says its okay to kill innocent humans?
Why did you choose to include the word "innocent"? See? THIS is same the ideology that ISIS uses. Of course, it doesn't say in the Qu'ran that it is permissible to kill innocent humans. It does, however, say it is not only permissible to kill complicit humans but requires the faithful to do so. And ISIS, in their own eyes, ARE the faithful. They are, in their own eyes, the only faithful. The only ones who are truly following their god's commands to the letter.
From an outsider's perspective, your ideology, as presented here, is the SAME as ISIS': it is not permissible to kill innocents, but it is permissible to kill those who are not innocent, especially in self-defense or in defense of Islam. Where you might differ is how you define "innocent".