For leftists --and for liberals in the long run, since liberals are usually just leftists who don't know it or want to admit it-- the State is their Church. Since for leftists there is no higher activity than politics ---politics is their religion, their ultimate totalizing narrative--- politics, the State as its embodiment, must needs dominate all of life.
The Liberal State, which we now have in America in spades, like all great Churches, makes moral demands on believers and unbelievers alike. For us, it is the great moral projects of anti-discrimination with which we live every day. Minorities and Women primarily, and then all the secondary and hanger-on focal points of Progressive Virtue: gays, immigrants, the disabled, the wounded planet, the 99%.
And all the Health and Safety commandments. Michelle Antoinette comes to mind, as well as the great AntiTobacco campaigns.
Every thought, attitude and behavior about these nodes of ethical enlightenment creates a challenge for us, to live up to the values and beliefs clung to and promulgated through the State Church. Without that constant reinforcement through law and the organs of Liberal Culture --media, films and TV, education, the compliant churches, the self-policing of decent people, etc-- who knows but that we would fall back into the sinful ways of our ancestors? Left free, only evil would result. No longer would we make ourselves believe that all ethnic and racial groups are equal or that anything a man can do a woman can do or that the gender of partners in a marriage is irrelevant. That way, as we know, lies the sad reality of History before Enlightenment.
Since the Constitution prohibited Congress from establishing any church as the state church, it eventually took over the role itself.