The issue of homo­sexuality is an open wound that the Church seems unable to stop itself poking. Every attempt to apply a salve only worsens the agony. The Pope’s expression of support for same-sex civil unions in a recent documentary, far from providing the basis for compromise, has only added to the sense of a widening schism. Gay Catholics welcomed Francis’ remarks; conservatives were appalled. And so the wound gapes ever more.

The entire issue is shaded by paradox. Catholic teaching on homosexuality is often assumed to be a primordial feature of doctrine, reaching back to the very beginnings of the Church. In reality, it is less than two centuries old. To be sure, hostility to same-sex relationships does indeed rank as a distinctive feature of Christian Scripture. In his Letter to the Romans, Paul paired men sleeping with men and women sleeping with women as comparable sins. Here, in the context of the age, he was doing something radically new. Never before had the category of same-sex relationships been defined in quite this way: as a unity. It is the measure of how novel Paul’s categorisation was that it took centuries for Christians even to find a word for it. “Sodomy”, which first began to be used widely in the eleventh century, signified not what we call “homosexuality”, but any deviant sexual act. It might just as well be used to describe bestiality or masturbation as anal sex. “Sodomite”, like “murderer” or “adulterer”, defined, not someone possessed of an inherent inclination, but someone who had surrendered to sin.