The Islamist ...

John Howard was in Washington in 2001 when the World Trade Centre twin towers collapsed and took with them more than 3,000 lives, and the Pentagon was attacked. He witnessed the spontaneous outpouring of emotion, then anger, then the fundamental changes in security and foreign policy. But even the PM agrees no event changed terrorism policy like the London bombings on July 7, 2005, which killed more than 50 people.

What made that event seminal wasn't the nature or scale of the attacks. Urban transport commuters were attacked in Madrid the year before. Suicide terrorism has a long and bloody history. What made London different were the perpetrators. All evidence points to the attack being the work of frustrated children of nominally Muslim migrants. These young men found themselves in what Peter Costello once described as a twilight zone where the values of their parents' old country have been lost but the values of the new country not fully embraced.

Ed Husain's autobiographical account, The Islamist: Why I Joined Radical Islam in Britain, What I Saw Inside and Why I Left, provides an insider view of the typical processes by which a small minority of the children of nominally Muslim Britons are radicalised.

Yet Husain's analysis also illustrates the limitations of the simplistic analysis of cultural warriors who presume what happens in Britain is exactly mirrored in other parts of the world. He shows the enormous impact of unique linguistic and cultural factors affecting different ethnic sectors of migrant Muslim communities.

Like more than three-quarters of British Muslims, Husain is of South Asian background. His parents are from the Sylhet region that forms part of the border of Bangladesh and India. His father follows a mystical Sufi order of one Pir Abdul Latif Fultali, with whom the author spent much of his childhood.

However, unlike many South Asian Muslim migrants (including my own parents), for whom language and culture are more emphasised than religion, Husain received a much more solid grounding in traditional Islam. Unlike his peers, Husain is able to recite the Koran with proper pronunciation and in accordance with the formal rules of recitation generally taught only in specialist schools in Egypt or Turkey.

His family's traditional Islam viewed itself as just religion, a private matter whose only public role was to make better citizens. It was only in high school religious education classes that Husain discovered another less familiar form of Islam in a widely used textbook written by the leader of a large British Muslim organisation.

This less familiar form of Islam treated the faith as a comprehensive way of life, an ideology that formed the basis of a movement for social and political change. This ideological Islam was associated with the Jamaat-i-Islami, a political party founded in India in 1941 by journalist and Islamist ideologue Abul Ala Maududi. After partition, the JI (not to be confused with the Indonesian Jemaah Islamiah) became an influential political party in Pakistan and wanted to transform the country into an Islamic state.

JI activism spread to the large South Asian diaspora in Britain, largely funded by Saudi petro dollars. Key JI institutions were built during the 1980s when JI-style Islam was deemed preferable to Iranian revolutionary Shiism and when the West and Saudi-funded Islamists were on the same side fighting the Soviets in Afghanistan.

JI activists may have controlled big London mosques, but could make little inroads on the views of migrant adults, many of whom regarded JI-style ideological Islamism as heterodox and fringe and also recognised its political agenda.

It was a different matter for the children of these migrants, however. Having been brought up in England away from a culturally Muslim environment and without the grounding in mainstream Islamic theology, these children saw JI-style Islamism as mainstream Islam.

Husain's book is about his navigation into various forms of Islamism, beginning with JI-style ideology and then moving on to the even more fringe Hizb ut-Tahrir (literally Party of Liberation and generally known in Muslim circles as HT). His rejection of his parents' mainstream Islam was caused less by any rebellious streak than his own naïvety and inability to recognise the fringe nature of Islamist ideology.

The book contains some inaccuracies. Husain erroneously claims HT was the ideological forebear of al-Qaida, a claim experts on political Islamism would dismiss. However, it is an elegantly written and honest account of one young British Muslim's journey into and out of different forms of political Islam. Cultural warriors will be disappointed by Husain's central thesis: that greater exposure of Muslim youth to mainstream Islamic theology provides an effective antidote to Islamism.