Liberalism was the dominant political movement that came out of the 17th century Enlightenment in western Europe.
It opposed heredity privilege, state enforced religion, and the Divine Right of Kings.
It supported science over theology.
It maximized individual freedom from the moral impositions of the state, which sought to impose a tightly defined set of traditions and protocols on the individual.
Liberalism is in contrast to Conservatism, which wants a powerful state to enforce the traditions and morality of the rulers, who were endowed by God to rule over the great unwashed plebes.
The French Revolution is the first modern instance of Liberalism. It sought to erect powerful individual rights in the face of government - with a focus on the protection of property, freedom of speech, freedom of the press, and a right to democratically choose your leaders.
Conservatives were deeply threatened by this because they didn't want to subject traditional & religious institutions to will of the people. Conservatives believe that freedom, individualism and democracy are dangerous because these things can overturn the sacred structure of society, including religion. This is why they opposed the Women's Rights Movement, the Sexual Revolution and the Civil Rights Movement. They saw the Women's Rights Movement as interfering with the sacred gender roles and hierarchy of the family (as intended by God, with the man as king of his home). Conservatives believed that women should be man's helper - clean the house, cook the food, and raise his children. In each instance where a marginalized group has asserted its freedom and right to self-determination, conservatives have opposed it.
Hitler opposed Liberal Tolerance because he thought it lead to the over-assimilation of Jews in prewar Germany. Hitler believed that Liberal Tolerance, by supporting multiculturalism, threatened the Real Germany. He believed that German Language, Religion, and Traditions were sacred - and that the Liberal Weimar Republic was destroying them by allowing a diversity of peoples and beliefs to thrive inside Germany. His political mission was to take back German Borders, Language and Culture. He believed that the German Liberals had allowed Jews to reach positions of power inside government, banking and entertainment - and that the anti-Christian beliefs of Jews along with their refusal to embrace the German language was destroying the Real Germany.
Understanding why Hitler hated Liberal Tolerance will help you understand Liberalism.
