Do you think ISIS is currently gathering intellectually disabled people?

I don't think a human action being particularly atrocious or surprising equates to mental retardation. You could argue that killing thousands in the atrocious and awful methods they do makes them less "human" or not "normal" but mental handicapped refers to an intellectual disability en.wikipedia.org/wiki/Intellectual_disability. There have been MANY very very smart (read: not intellectual challenged) people who have done awful things and have been deluded into believing awful things. So no I do not.