Is Islamic art mainly about geometry and calligraphy? Not at all, a controversial new exhibition of past masterpieces in London reveals. It can also be about erotic love of a very human kind. And could this fact help to fan the flames of controversy among fundamentalists yet again, after the Danish cartoons and Rushdie’s knighthood?

“I imagine that in certain puritanical Arab countries such as Afghanistan there might well be resistance to depicting the human form in the way certain images in this show do,” says Professor Azim Nanji, director of the Institute of Ismaili Studies in London. “But that fact would also belie the entire experience of Muslim art of the past.”

So there is the problem. The past may well be too tolerant – and too various – for some of the Muslim scholars of the present.

Take the depiction of physical love between the sexes depicted in a Mughal painting such as Lovers in a Landscape, for example, which was painted in 1646. Two lovers are leaning into each other. There is wine and a wine glass. The woman is repeatedly burning her lover’s arm. Physical love may well be a metaphor for man’s love of the Almighty, but there is no denying that this painting depicts passionate physical love. Could this be shown in Afghanistan today?

A few weeks earlier, Alnoor J. Merchant, the senior librarian at the Institute of Ismaili Studies in London, discussed the intricacies of Islamic art in Parma, northern Italy, where more than 160 objects from the Aga Khan’s great collections of Islamic art – coins, paintings, folios from the Koran, ceramics, musical instruments and much else – have just been on show at the 16th-century Pilotta Palace. Many of these pieces were on display for the first time.

This exhibition, give or take an object or two, called Spirit & Life, opens on Saturday at the Ismaili Centre in South Kensington.

Merchant, the exhibition’s curator, talks quietly and with discretion. The Aga Khan’s collection, he tells me, which has never been fully on display – it is stored in London and Geneva – is really two collections in one. The current Aga Khan’s uncle, Prince Sadruddin, began to collect objects in the 1950s, when he was a student in America. These were all examples, on paper, of the arts of the book – miniatures and examples of Islamic calligraphy. About ten years ago, the Aga Khan began to expand the collection. This is the first exhibition of works from the present collection.

Shamefacedly, I tell Merchant about my difficulties with Islamic art: that it often smacks of austerity; that it feels as if it is principally about geometry and calligraphy; that it lacks a kind of human vitality, and in part this may be because Islam forbids representations of the Prophet. Courteously, Merchant corrects my prejudices, making plain the art’s scope and achievements.

Islamic art is not one art, or even one civilisation, but many, he tells me. Austere? Not at all. It can be extraordinarily colourful. Yes, it is an art that is often deeply informed by the spiritual – but it is also alive. It is both an art of the mosque and an art of the great dynastic courts: the Mughal, the Ottoman, the Safavid and others. It combines the sacred and the secular.

The exhibition itself has an enormous sweep, geographically and temporally. It spans 1,000 years, from 900 AD to the end of the 19th century. It shifts from Spain down to North Africa, and east to China and Indonesia. There is not one art of Islam, but many, and they are hugely dispersed geographically.

“What we are trying to do,” explains Merchant’s co-curator, Benoît Junod, “is to present the arts of Islam in ways they have not been seen before. Usually it is a matter of presenting them either chronologically, by dynasties, or by material. We have tried to pull out and to illustrate specific themes, beginning with the Koran and then moving on to an examination of works from five particular dynasties. After that, we deal with such issues as music, pedagogy, the history of scientific development. We wanted the displays to be not only a showcase of beautiful objects, but to be instructional, too. Our ambition is to give some historical and intellectual perspective.”

At the Parma exhibition, beneath the great brick ceilings of the old palace, we begin with a section devoted to the Koran itself, all folios in different scripts. One Koranic verse has been painted in gold on to a sweet chestnut leaf. It is so fragile.

“Now what usually happens when a page of an illuminated manuscript is put on display is that you see just one miniature,” Junod says. “You are of course thirsting to turn the page in order to see others. When this show goes on display in London, plasma screens will enable you to see all 14 pages of one particular manuscript.”

In a section on education we find a 16th-century painted miniature in three parts: in the top section a master dictates to a prince; in the middle, two scribes discuss their work; at the bottom, paper is being burnished. Nearby, a miniature from the same source shows a school courtyard, with boys reading and writing. Remote in time, yet so familiar in theme.

The idea of educating the young may well be a familiar theme – but it is not one to be taken for granted under the resurgent Taleban.

Spirit & Life runs at the Ismaili Centre, London SW7 (www.spiritandlife2007.org, 020-7581 2071), until Aug 31

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