When we start with big universal ideas, at the level of concepts and -isms, we too-often stay there and argue about theory and generalizations. At that level, the mind is totally in charge. It is then easy to love humanity, but not any one person in particular. We defend principles of justice, but would not put ourselves out to live justly.
This takes different forms on the Left and on the Right, to put it in political terms. Liberals are often devoted to political correctness and get authoritarian about process and semantics. Conservatives can be overly loyal to their validating group for its own sake and become authoritarian about its symbols, defining and defending the rules and rights of membership in that group. Both sides risk becoming “word police” and “symbol protectors” instead of actually changing the world—or themselves—by offering the healing energy of love.
Sometimes neither group ever gets to concrete acts of charity, mercy, liberation, or service. We just argue about theory and proper definitions.
Start with loving one situation or one person all the way through. That is the best—and maybe the only—first school for universal love.