I've been reading Marilynne Robinson's book of essays, The Death of Adam: Essays on Modern Thought. Her essay entitled “Puritans and Prigs” sets out to defend the Puritans and contrast them to a group she calls prigs, the sort of politically correct thought police that the right used to rail against in the 1990s. I think her argument also has a lot in common with your indictments of fundamentalism and movement conservatism.
The Puritans' belief that we are all sinners, Robinson says, gives "excellent grounds for forgiveness and self-forgiveness, and is kindlier than any expectation that we might be saints, even while it affirms the standards all of us fail to attain." However, she argues that modernity, of which prigs are emblematic, is essentially Stalinist, in that it believes that society "can and should produce good people, that is, people suited to life in whatever imagined optimum society, who then stabilize the society in its goodness so that it produces more good people, and so on. First the bad ideas must be weeded out and socially useful ones put in their place. Then the bad people must be identified, especially those that are carriers of bad ideas."
. . .
Indeed, much the same could be said of today’s right. For my part, it seems all such prigs (left and right) stem from the fundamental epistemological arrogance of modernity--that all things can be known. This is as true of Darwinism as it is of Biblical fundamentalism. The older I get, the more folly such claims seem to contain. This is not a new insight: one need only look at Ecclesiastes. Efforts such as political correctness and movement conservatism are destructive of civil society and are based on nothing more than a chasing after the wind.
I think this is a brilliant summation of the problem with both the contemporary right and the contemporary left. Forgiveness and understanding are no longer virtues.
They've been replaced by self-righteousness and moral certitude . . .