We avoid situations that would force us to act upon our beliefs. We are all for brotherhood, but we stay clear of our brothers. This is in some ways normal. The resultant allegiances, he points out, bring out the best in man in terms of loyalty, self-sacrifice and charity. They also, however, bring out the worst.
Outsiders become threats to our basic needs of survival and security, of acceptance and self-esteem.
They become expendable. Prejudice is an adult disease. Nevertheless, its incubation begins in childhood. It doesn't take very long for a child to be taught that other people are different. It doesn't take very many years to establish strata of acceptability.