I suggest you get the critical thinking booklet series from www.criticalthinking.org Work through some of the exercises together. Then your son will be able to see through your family's machinations, even if you can't supevise him 24/7.
Excellent, jgnat!!! I have the whole set of booklets myself. It's wonderful "food for thought!"
WW, in addition to talking about your feelings and thoughts on the subject with your son, it will be good for him to actually see that you're not alone in your thinking by means of showing him from reliable psychology sources on cult descriptions and behaviors.