ISIL is not "evil". It is a group of people that does things that them or other humans might perceive to be "good" or "evil." None of them are incapable of doing the things that you people perceive to be "good." In reality, none of their alleged "evil" actions are objectively "evil", only subjectively "evil" based upon your delusions of morality.
The act of keeping women, or any humans, as slaves is not "evil"... but it can be perceived to be "evil" by someone who's moral perspective deems it so.
I do not feel the need to have my "religious beliefs" accepted by anyone. If I were to respectfully and privately engage in intelligent discussion with the wisest of ISIL's leaders, I'm sure that they would agr that "good" and "evil" do not exist, but that they are necessary delusions for the masses.
If ISIL attempted to impose their religion on me, I would gladly open my mind to what I could learn from Islam. I already find it to be a beautiful religion, and I already worship the same God, and believe in the same Angels and Djinn. The only difference really is the laws, rituals, and some slightly different "perspectives".
Why would I allow myself to be "converted"?
Because to truly understand a religion, one cannot look at it from the outside-in, but from the inside-out.
In the O9A, we call this "insight roles".
When we truly study a religion, we "convert" to it fully to learn all that we can from it... even that which goes against what we feel is our Nature. Through willpower, that religion's God(s) and laws and and Weltanschauung and belief system becomes your reality... for as long as necessary to extract and absorb as much wisdom, power, and experience from it as possible.
In Chaos Magick, it is called "paradigm shifts" although that usually refers to briefly accepting the Weltanschauung and/ or pantheon and belief systems of a religion for a specific ritual or working, using an extreme amount of willpower to convince yourself to believe in it fully... and then reverting back to your previous beliefs/ religion/ spirituality/ Weltanschauung when the ritual or working is over.
If one seeks to explore the use of paradigm shifts, it is best to have first truly enlightened yourself to that particular religion from the inside-out through the masterful use of insight roles.
An insight role or a paradigm shift is similar to a "split personality", and from a certain perspective... it can be just that. Except it is controlled through Willpower.
And once you have become familiar with insight roles and paradigm shifts, and have absorbed enough knowlege and wisdom about the forces Above, Below and Within... then one can truly begin to explore such things as Spiritual Invocation aka Spiritual "Possession".
I do not care if people consider my spiritual practices "morally" acceptable. I do not strive to be what others consider to be "good". I do not strive to be what others consider to be "evil". I strive only to follow my own True Will while seeking guidance along the way from what I perceive to be the forces Above and Below and Within.