When people are taught from birth that they are superior to a certain other subset of humanity, the notion becomes an unshakeable part of their character. Humans naturally want to feel superior to other humans. Those people from that neighborhood, those people of that religion, those people of that political party, those people with that skin-color. The idea is to always feel that no matter how bad my life is or how much of a failure I am, I am not one of them. As long as you are not one of them, you have not sunk to the lowest low, there are still other people further down. It is where most people get their self-esteem.
What happens when there is no clear evidence of superiority? What happens when circumstances force you to acknowledge the humanity of the other person? That’s when you move away. You segregate. One of the main purposes of segregation, across economic, religious, or racial lines, is to avoid recognizing the other group(s) as equals. There is a loss of identity and people start to integrate when this happens. When you lose your identity as a specific group, then you lose the self-esteem associated with it. The source of your sense of superiority, therefore, is a carefully maintained ignorance of other racial, religious, and ethnic groups.
Bigots are not accidentally ignorant. Their lack of knowledge of other cultures did not come about because they are simply too lazy or unequipped to learn. It is a deliberate human behavior, a psychological device, to avoid discouragement of the individual, to bring people together, to maintain a sense of predictability and safety.
How divisive tactics like race-baiting really work
Demagogues and fomenters use one simple tactic: to weigh the need for self-esteem, to consider yourself better-than, the need for consistent, safely homogenous communities, against logic and fairness. Logic and fairness dictate that people be fair and react to individuals individually. You assume equality, at least until proven otherwise conclusively. By putting the two on the scales together, the race-baiter is asking you to choose between an inflated sense of your personal worth and being rational. Being rational always loses.
The divider calls upon what is already there, the needs and fears and desires, he does not insert them. Hitler did not make the German nation do anything that it was not already inclined to do. He merely focused already existing emotion and used to fuel specific actions. The leaders to inspire ethnic cleansing merely harness the forces, they don’t generate them.
The real solution to racism is not teaching about the equality of people, or “tolerance”, it is about giving people ways of feeling valuable and important apart from being a member of an ethnic group or religion. Failing that, you need to have an overwhelming necessity that renders all divisions irrelevant. You need motivations for forming communities, beyond income-level, race, and worship. Dictatorship, natural disaster, religion, and war are basically the only things known to have accomplished this.