One of the ways our defenses enable us to preserve outdated mental models and beliefs about ourselves and others is to align with belief systems shared by groups. Using an extreme example, there are many groups and ideologies that share justifications for hating those who are not like them. If the early environment of a child required them to give up too much and greatly restricted or eliminated avenues for expressing frustration then they are often left with large stores of un-discharged potential anger in search of a target. Ironically, the best targets tend to be others who express the unrealized parts of the angry “child” now impersonating an adult.
We don’t want to see in others what we have given up in ourselves, especially if joyfully expressed, so we tend to discount them as a way of preserving our illusions about ourselves. In others words what we most dislike or hate in others are often the unacknowledged or missing parts of ourselves. When we see in others what we don’t want to see in ourselves it stirs what is missing and threatens the fragile alliance with childlike perspectives that support illusions about ourselves and what we want to believe the world is really like.
But ideology or belief can be based on adult choices as well. Since one can only challenge a belief in the name of another belief, the acid test boils down to how this question is answered: Is there room for others who have different mental models and beliefs to be valued as equally worthy even though their beliefs and actions are different than those we hold to be true?