Thursday's coordinated terrorist attacks that killed at least 49 people have underscored competing forces within Britain's Muslim community: a minority that advocates violence against Western targets, and those who want to coexist peacefully with Britain's multifaith, multiethnic society.
Since the bombings, the media and Muslims have been at pains to explain that most of the country's 2 million Muslims are peaceful. "The Muslim community in Britain has a long history and is enormously diverse," says Anas al-Tikriti, a member of the Muslim Association of Britain.
But the attacks are turning attention to the increasing numbers of young British Muslims who are rejecting their parents' traditional culture in favor of a radical and expansionist Islam. This strikingly Western version of Islam combines an independence of thought with a contempt for established traditional scholarship and a theme of teenage rebellion.
"Getting involved in radical Islam is an emotional thing rather than a rational decision," says Abdul-Rahman al-Helbawi, a Muslim prayer leader. "And it's not a matter of intelligence or education - a lot of these radicals in Britain are very well-educated."
In Dalston market in north-east London on Thursday, "Abdullah," a Muslim watch-mender and evangelist, was in a pugnacious mood.
"We don't need to fight. We are taking over!" he said. "We are here to bring civilization to the West. England does not belong to the English people, it belongs to God."
Two days later in a prosperous West London cafe, Mr. Helbawi pondered the attacks. "It's not a surprise but I am still shocked," he said. "How can they do this? London is a city for all the world. This is not Islam."
Hours after the bombings, Helbawi logged onto an Internet chat room run by British Muslim extremists. "They were all congratulating each other on the attacks," he said. "It was crazy. They were talking about how they had won a great victory over the infidels, as if they had just come back from a battle."
Although so far, there is no evidence that British Muslims were involved in the bombs, there is little doubt that many British Muslims feel that Britain "deserved" the attacks for supporting the US invasions of Iraq and Afghanistan.
"Because Muslims explain the conflicts in Iraq, Kashmir, and Israel through Islam, every Muslim feels involved," said Helbawi. "People watch television and see Palestinian women being hit and pushed around by Israeli soldiers, and get angry and feel that they have to do something."
But beyond anger, a sense of alienation often drives radical Islam. Many second- and third-generation immigrants find themselves cut off not only from their parents' cultures but also from a British one that includes alcohol and looser sexual mores.
"If you don't drink, it really cuts you off from English society," says Ummul Choudhury, a London-based Middle East analyst for the Gulf Centre for Strategic Studies. "The view of the older generation is also that you do not integrate. If you do, you are told you are betraying your culture and religion."
The resulting isolation makes it easier for young Muslims to develop a contempt for British society.
"There is also a lot of racism toward white British people," says Ms. Choudhury. "It's not really something that people want to talk about, but there are definitely some things that Muslims say between themselves that they would never say in front of white people."
For frustrated and isolated young Muslims, radical Islam is not difficult to find. Girls in particular are often prevented from going out at night and can be easily drawn into online Muslim communities where they come into contact with other disillusioned Muslims from across Europe.
One leading analyst of the Islamic diaspora even compares the lure of extremist Islam to 1950s teens listening to Elvis in an attempt to shock their parents. "The son of a Pentecostal preacher in Brixton was recruited by the radical Muslims," says Nadhim Shehadi, acting head of the Middle East program at Chatham House.
"This young man initially tried to upset his parents by becoming a rapper," says Shehadi. "But when his parents stopped objecting, he became a jihadi instead."
The antiestablishment nature of this new Islam and its apparent status as an alternative to capitalism and secularism is also winning converts among native Britons.
"People come to Islam from all walks of life. It's not just middle-class people but also electricians, judges, and taxi drivers," says Sara Joseph, the editor of "Emel," a lifestyle magazine for Muslim women, who converted to Islam at age 17. "The main catalyst for conversion is often going out with a Muslim, although the primary factor is usually a search for spirituality."
While the estimated 1,000 British Christians, atheists, and members of other faiths who convert to Islam every year are often attracted by Islam's clearly defined teachings, this minor trend is overshadowed by Muslims' highbirth and immigration rates, which tomany Muslims promises increased political and social influence in the future.
Indeed, taking advantage of Britain's rapidly expanding and increasingly Muslim population are new parties that aim to promote ethnic and religious agendas. One is Respect, a left-wing party founded by former Labour MP George Galloway, that aims to unite Muslims and socialists around opposition to American foreign policy and globalization.
Linked to the desire for increased political power are attempts by some radical Muslims to begin a process of Islamicizing British cities.
Last month, Muslim groups in Glasgow petitioned the City Council to ban an Italian restaurant from serving alcohol to diners seated at outside tables. Hospitals in Leicester considered banning Bibles from hospital wards to avoid offending Muslim patients. In Birmingham, a group called Muslims Against Advertising began a campaign of painting over billboards that they deemed offensive to Islam - targeting ads for Levi's jeans, perfume, and lingerie.
But these small campaigns are polarizing public opinion along ethnic and religious lines - and creating support for Britain's far-right groups, who present themselves as defenders of Britain's hard-won freedoms.