We’ve been here before, says John L Allen Jr, as the arguments continue.

After years of ferment in Catholicism over a highly sensitive matter of sexual morality, marked in almost equal measure by both expectation and dread of a possible change in official teaching, the Vatican issues a landmark document seeking to resolve the issue.

Reaction is both instantaneous and volcanic, with blowback coming not just from individual pundits and commentators but, at times, whole groupings of clergy and bishops. Taken together, the document and its aftermath seem to suggest a badly-divided Church and a pope struggling to contain the revolutionary forces he himself has set in motion.