“Humans appear to have an inbuilt, almost irresistible tendency to divide the world into “us” and “them,” good guys and bad, in-groups and out-groups. We see this everywhere: in politics, in religion, in sports and national pride. For Jesus, the poor and downtrodden were the in-group and the Pharisees and the rich the out-groups; for Marxists (much as for Jesus), the working class was the in-group and the ruling class the out-group; for the Nazis, the Aryan race was the in-group and Jews the main out-group; and for some radical feminists and “lesbian separatists,” women are the in-group and men the out-group.”