I didn't say anything about Iraq, but the fact Obama pulled out of Iraq before it was stable is one of the main reasons we ended up having to go back and take care of Isis to begin with. Once we were in we should have finished the job at least and left a decent force there to assist in stabilizing the area. Whether we should have gone there to begin with is an entirely other story, but you'll have to talk to Intelligence about that. I can tell you that there's no guarantee that toppling Saddam caused the rise of Isis, it very well could have happened regardless if you look at the history of radical Islam...and given their power and what they accomplished at one time I think it's safe to say Saddam wouldn't have been enough to stop them.
If you’re interested in this I would highly recommend Frontline’s The Rise of Isis along with Bitter Rivals. The second one examines Iran and Saudi Arabia and explores the shift of the Saudi’s toward a much more conservative world view beginning with the violent insurgency that occurred at Mecca in the late 70’s.