The bad news is that they apparently thought it would involve killing Christians, Jews, Hindus, Buddhists, and Yazidis--among others too numerous to mention:
“The whole jihad was turned upside down,” the militant recently told Shiraz Maher, a senior researcher for the International Center for the Study of Radicalization at King’s College London. “Muslims are fighting Muslims. I didn’t come for that.”
Yeah, well, the jihad is what it is, eh?
I wouldn't worry much about deprogramming them. Killing them wipes the memory nicely.