The de-Christianization of France was a direct consequence of a century of skepticism and relativism.

Photo: Topkapi Serail.

Dedicated to it at the heart of a museum that can honestly claim the Enlightenment as parent. The British Museum was founded in 1753 as a public institution where you could see all manner of natural and artificial curiosities, as well as read books. When the museum was separated from the British Library in 1998, the King's Library - the gilded gallery built to house George III's book collection - became vacant. Now it is the home of a new permanent display that resurrects the Enlightenment museum, in which Neil MacGregor, the director of the British Museum, hopes to create a centre of global citizenship nurturing "dialogues between civilizations". Before visiting this exhibition we might consider how unsettling and liberating "dialogues between civilizations" 250 years ago could be. People said things in the 18th century that are still risky today.

Especially about religion. The de-Christianization of France was a direct consequence of a century of skepticism and relativism. Voltaire's Philosophical Dictionary, published in 1764, was attacked, banned and read avidly across Europe. It's not hard to see why it remained on the Vatican's index of forbidden books until the index was abolished. The book's title is misleading: its alphabetically organized subjects (Atheism, Chinese Catechism, Fanaticism, Superstition, Toleration) provide neither a comprehensive digest of philosophical thought nor an explication of philosophical terms. Voltaire's theme is religion and his project is its philosophical critique. He ruthlessly exposes the historical implausibility of the gospels. Why, he wonders, does the ancient Jewish historian Josephus fail to mention so important an event as the life of Christ? Why, in his comprehensive account of the cruelties of Herod, does Josephus omit the Massacre of the Innocents? Gibbon subjects Christianity to a similarly withering historical critique in his Decline and Fall of the Roman Empire (1776-88). He ironically praises the early Christian ascetics. "The acquisition of knowledge, the exercise of our reason or fancy, and the cheerful flow of unguarded conversation may employ the leisure of a liberal mind. Such amusements, however, were rejected with abhorrence or admitted with the utmost caution by the severity of the fathers..." Gibbon is the Jane Austen of doubt, wittily chronicling Christian absurdities. One contemporary reader, James Boswell, called him "an infidel puppet". There was more to this denunciation than meets the eye. Not only did Gibbon criticize Christianity, he admired Islam. "The base and plebeian origin of Mohammed is an unskillful calumny of the Christians," begins Gibbon's sympathetic account of the rise of Islam. He praises Mohammed as an orator and a leader, and respects the Koran. For Gibbon, Islam is attractively free from the hysterical superstitions of Christianity, tolerant in its acknowledgement of earlier prophets, including Christ. "The Koran," he writes, "is a glorious testimony to the unity of God. The prophet of Mecca rejected the worship of idols and men, of stars and planets..." Gibbon's praise of Islam is strictly on his own terms, though. Just as Voltaire reinvented Confucianism in his own image as rational philosophy, so Gibbon imagines Islam as a religion for skeptics. "A philosophical atheist might subscribe the popular creed of the Mohammedans," he says provocatively, "a creed too sublime perhaps for our present faculties." There was a cult of all things "Mohammedan" in 18th-century Europe, just as there were cults of China and, at the end of the century, ancient Egypt. But this went beyond building pagodas, mosques and mini-Alhambras. The most radical thinkers systematically juxtaposed the world's belief systems in order to show that insights, as well as fallacies, were common to all. They were, to use the modern word, relativists.

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