Ideological fanaticism and religious fundamentalism are atavistic expressions of human behavior

 Because they reflect chronic deficiencies or incapacities, linked to the most advanced thought that human beings can achieve, which is rational thought: reflective, self-critical, self-aware, objective, impartial, thoughtful... Which best enables us to improve our true understanding of the world... Because they reflect emotional instincts projected into language, in which they take the form of words and concepts and emulate human intelligence, hiding their much simpler and vestigial nature: an atavism of the mind, as if an animal of another species acquired the ability to learn our complex language but used it only to reinforce its instinctive impulses. In this case, in the real world, when dealing with humans themselves, a very common and little understood mismatch, often considered as an exclusive social or cultural phenomenon and not, or mainly, as a cognitive and evolutionary phenomenon, of something deeper that does not affect us equally if this also depends on the predispositions we present, to which some, or many, are more susceptible than others. Therefore, the more irreducible the individual is regarding his personal beliefs, especially those that are categorically irrational, the more guided or dominated by his emotional instincts he is. Wouldn't there be logical reason to believe in nonsenses that can even be easily refuted or at least severely problematized, from the belief in eternal life and divine existence to the secular belief in absolute human equality, for example. If the only logical reason I have found to explain this support for irrational beliefs is the apparent or felt personal benefit of doing so, but also because it reflects a self-projection of expectations and personality traits of the person themselves, of something they believe as a reflection of themselves, like an intoxicating state of excessive self-confidence, which leads to a less sober state. That is why it is so dear to a person afflicted by this delusion of grandeur to criticize, test and/or give up even their most irrational beliefs, if for them it would be similar to mutilating their own body, cutting and throwing away their own pieces of hope, dreams, motivation for life and sense of reality, even if falsified, and making room for facts or truths that they would not like to have in their mind as part of their personal belief system, which do not share their way of being and thinking.