Of course all children should be taught good critical thinking. Of course. And of course that would cut down on the number of people caught up in cults.
The trouble is that many cults indoctrinate people by very slowly and systematically dismantling their their critical thinking by using using tricks of the mind.
There is a bit of covert hypnosis that goes on. At bit of short-circuiting the brain. An attack on the mind.
A certain percentage of humans are, by nature, very suggestible. These people can have their minds tricked despite having been taught critical thinking skills. Watch Derren Brown convince a person that red is black or some other such nonsense. Their brain believes red is black because it has been tampered with...it has been tricked with covert hypnosis, not because of lack of critical thinking. (also notice how Derren Brown uses the subject's emotions as tool to manipulate her mind, to disable her critical thinking. He doesn't play on emotions, as we might suspect he would. Rather, he uses emotions as tools to manipulate her thoughts. It is quite diabolical, and disgusting, really.)
In fact I think that under the right circumstances almost anyone can be a victim of this sort of thing. And I do believe cults employ some of these tactics.
Of course good critical thinking skills will help lessen the risk. But a person also has to be...on alert...aware at ALL TIMES that this kind of mind trickery is out there so that they will not be fooled. It only takes a split second of the tinyest bit of misplaced trust and your mind can be manipulated by those who want to control your thought so that you think red is black...or that bad is good...or that giving them all your money is a good idea...
but then, of course, a very good education in critical thinking would include information and warnings about this sort of mind trickery.
So yeah. Critical thinking = good. I'll stop rambling now.