Of course liberalism/progressivism is a religion. From Robert Hall at American Thinker:
Psychologists say that people need religion in one form or another, and will always invent a theology if they are not given one. I’m not the first to notice that the rise of thetic, unchurched, Godless Secular Humanists has resulted in liberals meeting this human need by converting Progressive Ideology into religious doctrine and admiration for Progressive leaders into unquestioning worship. Self-righteous calls for civility aside, this explains why they get so angry and vicious when you challenge any of their tenets. You are not disagreeing with them over policy. You are attacking the core of their religion, and their reaction is often the same as if you told a member of the Westboro Baptist Church that Jesus wasn’t divine or a member of the Muslim Brotherhood that Mohammad was a fake. Blasphemy cannot be tolerated by fundamentalists of any stripe.
Of course, like all religions, the Progressive Church has degrees of belief, from the moderates, who are rather like Christmas and Easter Christians, to the Fundamentalist Progressives, who respond as you’d expect from a Salafist told that Allah wasn’t really in favor of slaughtering Jews. (Why are you picking up that stone?)
Read more: American Thinker