This month we marked two grim anniversaries. Ten years ago, on July 7 2005, British Muslim suicide bombers killed 52 people in London. Inspired by Osama bin Laden, the four men apparently believed the attacks were a religious duty. Ten years before then, from July 11 to 13 1995, a Serbian militia massacred 8,000 Muslim men in Srebrenica - the largest mass killing in Europe since the Second World War. The Serbian leader Slobodan Miloševic had for years been stirring resentment among Orthodox Christians by reviving memories of their defeat by Muslims at the Battle of Kosovo in 1389. We could explain such behaviour in terms of political or ethnic rivalry, but the discomfiting truth is that their faith in God liberated these killers from ordinary morality. In the words of Pascal, who saw much bloody conflict between Catholics and Protestants during the 17th century, "Men never do evil so completely and cheerfully as when they do it from religious conviction".
Jonathan Sacks, Chief Rabbi until 2013 and doyen of Radio 4's Thought for the Day, is troubled by the dark side of faith. His new book tries to explain why religion and violence so often go hand in glove. Unsurprisingly, he does not believe, as Richard Dawkins does, that religion is essentially violent and would be better abandoned. (Nazism and Stalinism had nothing to do with God.) Nor does he say that his religion is peaceful while that of his neighbour is violent. In fact, that sort of black-and-white thinking, he argues, is exactly what leads to hostility between religions.
The explanation lies in religion's dual nature. The three great monotheisms - Judaism, Islam and Christianity - are spiritual belief systems that encourage prayer, charity and forgiveness. But, says Sacks, they are also tribal identities whose "noble sentiments have often been confined to fellow believers, or at least potential fellow believers". Once a religion becomes an identity and builds a community, conflict will ensue. Under Christian rule, Jews were either persecuted or allowed to live in sufferance until they converted; under Muslim rule, Jews and Christians were tolerated at various times, but treated as secondary subjects with restricted rights to worship.
The religious paradox is that while prophets and saints preach worldly detachment, the most successful religions have been attached to earthly powers. In Sacks's words, religions have often lusted after "power, territory and glory, things that are secular, even profane". It is all too easy to think that serving God means making everyone else worship as you worship. At its most extreme, this becomes what Sacks calls "altruistic evil: evil committed in a sacred cause, in the name of high ideals".
One blatant example of "altruistic evil" is the so-called Islamic State, or Isil. The barbarity of its crimes are all the more disturbing for the righteous language in which they are cloaked. For Muslims especially, it is profoundly disturbing to see the declaration of faith printed on their black-andwhite flag. The contrasting colours are not accidental. Isil propaganda regularly attacks what it calls "the grey zone": a place of moral ambiguity to which it believes the world has succumbed. That is why it urges culturally confused Western Muslims to leave their homes and build a pure caliphate - a message that, to date, about 700 have heeded. But as Sacks rightly points out, the Qur'an celebrates human diversity rather than wanting to stamp it out: "Had God Willed, He could have made you one community. But in order to test you with what He has given you, [He did not]. So compete with one another in good works."
For Sacks, only a subtle reading of scripture can save religion. He interprets the sibling rivalries in Genesis as a model for competition between Jews, Christians and Muslims. God might have chosen Isaac, says Sacks, but his brother Ishmael joined him to bury their father Abraham; Jacob might have stolen Isaac's blessing from Esau, but the hairier brother is also blessed; Judah tried to kill his brother Joseph, but is forgiven. This is Sacks's "theology of the Other": keep your own faith and identity, but acknowledge the stranger as your brother.
His broad vision has much to recommend it, and the book is argued with erudition and passion. But I have a couple of caveats. What about those who are not religious? He doesn't really engage with liberal ideals such as universal human rights that offer an alternative ethic to religious group identity. The second is that he says little about Palestinians living under Israeli occupation. In fact, the case of Israel, which was created to preserve the Jewish people in the wake of the Holocaust, but in doing so dispossessed another group, is an excellent case study of the paradox of religious power.
Sacks is undoubtedly right, though, to warn about the real threat to non-Muslim minorities in the Middle East. A hundred years ago, 20 per cent of Arabs were Christian; now that figure is only four per cent. As nation states fall and extremism spreads, religious diversity in the region will decrease. This would be a catastrophe for the victims, but it would also be a tragedy for Islam to be deprived of its sibling faiths, whose scriptures it reveres and prophets it follows. We can only pray that the story turns out more like Isaac and Ishmael than Cain and Abel.
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