Actually the 'what would need to happen for you to question your belief system? ' question is straight out of one of his talks on youtube.
Yes, thank you for reminding me. That is one of Hassan's questions.
Here's a question/direction you might take. Talk about the Mormons.
Questions, such as: "What would a dedicated Mormon have to do, in order to learn that his church is flawed?"
An honest answer would include "reading literature considered apostate by the Mormon leadership".
Once he's ready to actually read something, Ray's first book is the very best choice, IMHO. Mickey Mouse suggests Don Cameron's book, and it's excellent. However, Don's book is hard-hitting from the first page. He doesn't pull any punches. Some have told me that it would have scared them to have read Don's book in the very beginning of their journey.
One of the questions that I grappled with, early on, was, 'What if the JWs are wrong? How would I ever know?'
Ultimately, it involved overcoming the FEAR of induldging my doubts. Hassan talks about helping people to overcome the fears and phobias implanted into them by the cult. The fear of being misled by Satan, the fear of apostates, the fear of losing eternal salvation, etc.