Modern liberalism, as opposed to classical liberalism, is inherently racist. They cannot help but put people into groups and judge the individuals within based on their skin color, religious beliefs, political affiliations, hobbies (hunting, fishing, etc.), employment/business ownership, sexual orientation, etcetera, etcetera, etcetera. The thought of actually accepting people as good and decent people who may disagree with you is anathema to the liberal mindset.
One of the best example of liberal thinking I have ever seen was a gay rights militant responding to a Christian's statement that we are all sinners before God. The gay guy screamed, practically cried "So, you're calling us sinners! You're a homophobe!"