For a quick summary on understanding the very real, unmet needs and mindset of people who join cults, please consider the concept of Kinship.
A sense of belonging is in the middle stage of the ego developmental structure. If one doesn't have a sense of tribe, or family, one remains developmentally stuck and not mature. Sometimes, for example, a person may be 'unacceptably' homos
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"Cults," Sects, and "New Religious Movements"