Let your liberal friends know that the utopian ideas in their heads doesn't and never will reflect reality. This is because human nature doesn't change. The Consitution doesn't need to evolve because in 200 years, human nature has stayed the same.
Part of reality is: What is less abstract and more concrete. It is not based on feel-goodist ideas that attempt to equalize society. It is based on what works best. Conservatives know no perfect society can be produced or enforced by government. How can government make people become more moral?