They tend to act the most like their morality is something objective and universal, and that their morality must be imposed on others. The ones who claim nonsense like morality is "objective" tend to act most like moral relativists, changing their minds constantly, and being least serious about imposing their morality on those who dissent and acting like theirs is the only valid opinon. Christianity tells people to be like communists, but Christians tend towards capitalist thinking. While communists are the people who most strongly reject Christianity. It's a really weird world.