Not at all surprising. Voice hearing is often a sign of psychosis. And religious fanaticism is sort of a mental disease disease in itself. Cf. this article by Patrick McNamara: The god effect (see: http://aeon.co/magazine/psychology/dopamine-marks-the-line-between-religious-believer-and-fanatic/ ).
Religion spawns both benevolent saints and murderous fanatics. Patrick McNamara ia asking: Could it be different dopamine levels in the brain that drive that switch? Especially in a neural circuit/network involving strong connection between the amygdala, the nucleus accumbens and parts of the prefrontal cortex (PFC).
The amygdala is responsible for emotional activity and reactivity. Specific areas of the PFC are associated with emotion regulation and critical thinking skills.The nucleua accumbens is center for reward sensitivity. Too much activity (= hyperactivity) in this brain circuitry/network makes you over-creative (= you’re not inhibited by any limitations), which in turn can transform you to a (religious) fanatic.