Jesus never mentioned homosexuals, masturbation or the role of women in social, let alone sacred, life. Yet that hasn’t stopped millennia of godly scholars and lay Christians acting as if he had. According to these finger-waggers, extrapolating from biblical apocrypha, exegesis and their own personal fantasies, women are either morally superior or corrupt whores. Likewise, same-sex love is at one moment the emotional glue that binds celibate monastic communities and at another a sin that requires participants to be stoned.
In this masterly book, the ecclesiastical historian Diarmaid MacCulloch sets out to show that the source for Christianity’s confused teachings on sex, sexuality and gender is its own untidy DNA. Woven lumpily from two distinct traditions, Greek and Judaic, each crafted in distinct ways for at least a century before Jesus’s putative arrival on Earth, the Christian church remains an essentially heterogenous affair. MacCulloch conceives it as “a family of identities”, by which he means Roman Catholic, Protestant and Orthodox, as well as a myriad other sects and splinter groups, some of which have long disappeared. And, like all families, there has been tremendous potential for bickering and bad feeling. This is obvious enough when the subject for debate is, say, the precise nature of the Trinity. But introduce human genitalia as the topic under discussion, and the result is slammed doors and sullen silences.
Even at this remove and working from texts that have been washed through several translations, you can still feel the tightly wound twist of anger and desire at work whenever an individual theologian marches into the classroom to offer sex ed. Take John Chrysostom, AKA Golden-Mouth, who was bishop of both Antioch and Constantinople in the fourth century and obsessed with sexual relations between men. A modern critic has worked out that Chrysostom wrote more about sex than any writer before Freud except an obscure 12th-century Benedictine called Peter Damian (this impulse to tot up the smutty references in old books seems in itself a tad obsessive). It was Chrysostom who came up with the rule that “passive homosexuals” forfeited their right to be considered men and should therefore be stoned to death.
Meanwhile, Saint Jerome, writing from Rome about the same time, specialised in getting hot under the clerical collar about female heterosexual desire. He explained to one widow that if she remarried it would be “like a dog returning to its vomit” and that having another baby would only mean more poo to clean up. All of which tells us more about Saint Jerome than the lived experience of the woman he was hectoring who, one can’t help noticing, was called Furia.
Other sexual debates have been less scatological but no less bodily. In the early years, there was a long and solemn conversation about which of Mary’s orifices the Holy Spirit used to get her pregnant. A suggestion probably from the second century posited the eyes as the place where the spirit entered. An anonymous Egyptian authority suggested the nose, which sounds ticklish. The point of these theories was really to keep Mary’s sex organs decently shrouded. This was not only to make paintings of the Annunciation more seemly, but also to ensure the Virgin’s virginity remained intact. Yet even this careful scaffolding couldn’t solve the question of whether the act of giving birth to Jesus wouldn’t have ruptured the Holy Mother’s hymen anyway, making her virginity moot. It was a conundrum that kept clever men busy in their libraries for centuries.
You could be forgiven for thinking that it was only the early patriarchs who felt entitled to cast a theology in their own image. But as MacCulloch carefully shows, resourceful women found ways of subverting paradigms to their own pleasurable ends. Catherine of Siena, the 14th-century mystic, rapturously imagined herself marrying Christ using his circumcised foreskin as her wedding ring. Another Dominican nun, Adelheid of Frauenburg, wrote about her longing to be suckled by the Virgin Mary.
This sort of thing quickly gets embarrassing, and it was to neutralise the feverish imaginings of canonised celibates that the church pivoted in the early modern period to promoting family life instead. In the various Reformed churches, marriage now became the highest good, not just for devout congregations but their clergy, too. Anxieties about Mary’s hymen and Joseph’s cuckoldry were replaced by an ideal family modelled on that of a well-to-do tradesman’s in a northern European city. Jesus acquired some siblings (they had previously been shadowy), and there was a newly discovered grandmother in the form of Saint Anne. Even Mary Magdalene could now be rehabilitated from a whore with seven devils inside her (according to Luke’s gospel) into a slightly racy aunt.
It is these enduring Christian “family values” that have come to seem increasingly damaging. MacCulloch deals candidly with the clumsy and often cruel way in which churches in the post-second world war period dragged their feet on contraception, gay and lesbian rights and the ordination of women. His book is not in any sense a campaigning document, but he concludes with the mild and sensible suggestion that what is desperately needed is a general agreement that the church’s teachings on sexuality have little to do with scripture and everything to do with the muddled fears, fantasies and self-interest of subsequent commentators and the historical societies in which they lived. The best thing to do now would be to look beyond the old and often damaging dogma and take proper notice of how real people, in all their splendid variety, organise their sex lives most comfortably when left to their own devices.
• Lower Than the Angels: A History of Sex and Christianity by Diarmaid MacCulloch is published by Allen Lane (£35). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.