James Nicoll and his commenters are an education in themselves. In one post I come across 'Pecksniffian', a word I'd heard but never bothered looking up, and 'sedevacantist', which I'd never heard of at all. Latin might have given me a clue as to the latter- 'the seat is empty' ie we don't have a Pope, except we do have a pope, but certain reactionary Catholics hold that there have been no legitimate popes since Pius XII died, because all his successors have espoused the 'heresy' of Modernism. Including John Paul and Pope Palpatine, which gives you an idea of how ultra-reactionary reactionary Catholics can be.
Pecksniffian I'd need to read Martin Chuzzlewit to know, but it's basically a variant of hypocrisy as regards benevolence and morals.