You don't win ideological Turing tests by speculated about possible theories which you can came up with in the ivory tower. You instead need to read about the actual reasoning of the other side.

With ISIS the best article is likely Graeme Wood's What ISIS Really Wants. If you generally want to understand radical Islam Sayyid Qutb's Milestones is an insightful book as it lays out the general doctrine of modern Salafi jihadism.

ISIS does have intelligent leaders but those leaders also happen to be very religious. If you don't understand that religious framework I don't think you will succeed at winning any ideological turing test.