Subtlty is the only way to go about it. Accentuate his fears, and LISTEN TO HIM COMPLAIN, always seem objective but get him to make the calls. I'd fade slowly away, or invent an ailment...worked for me. You have to hit them at the right time with the right information.
Call it personal study at first, then hit him with the crazy-mind bending JW falacies one by one. The house'll start to crumble.
ashi