> To be honest, I still don’t fully understand how ideology can cloud the mind so thoroughly that only a single way of thinking remains possible.

From what I know, and please correct me if I am wrong; it relates to fear and cognitive dissonance. First, by creating FUD the perpetrator can cause physical narrow-mindedness within the brain, the amygdala — centre of emotions if you will — takes control which reduces reasoning capabilities. Second, by introducing multiple conflicting viewpoints in that state, you induce what we call cognitive dissonance. The brain is unable to reconcile the two opposing (or even just differing) views. This is a conflict at the circuit level of the brain, and the brain needs to reach a conclusion, and conveniently the conclusion is produced by the perpetrators of fud, those who seek to control/exploit others.