1) IQ doesn't correlate to intelligence, just a type of cerebral prowess or virtuosity (usually revolving around the manipulation of symbols, which leaves other aspects of our cerebral capabilities, such as musical ability for one). Given that, all it takes to make an high IQ person adopt the most retarded and absurd of ideas is to make it very enticing to them by adding layers of cerebral complexity and difficulty, at which point the cerebral becomes the object in and of itself, anything pertaining to truth or reality being seen as completely secondary or besides the point altoghether. Schuon said it best when he said modernism is about saying profoundly stupid things in the most intelligent way possible.
2) Intelligent people are more prone to see the relativity and complexity of physical reality, to sense the ephemeral nature of Maya and to seek out something that is universal and absolute, but in the absence of a proper spiritual and transcendent path, they end up seeking the transcendent on the level of relative manifestation, which is the chief source of satanism in the world. Less intelligent people are sort of immune to such aberrant deviations and their thinking leaves less room for errors, paradoxically enough. Their understanding of things may not be particularly sophisticated but it may still be far more correct or closer to the truth than any of the highly sophisticated specimen of pseudo-universalism moderns are so fond of.