Watch the inspiring "Caging Terror" documentary on Sunday at 2.30p.m. GMT.
London (CNN) -- To see Usman Raja before a cage-fight is to see a man in his element. As scantily clad dancing girls parade around and fast paced techno-music blares through the venue, and rows and rows of mostly white working class spectators eagerly await the contest, Raja is in a side room prepping his fighters, sparring with them, and reminding them of the importance of technique.
It is a brutal and intensely physical sport. One of his fighters, a towering muscular Pole reaches the heavyweight title match that day, during which he pulverizes his opponent with a volley of powerful kicks and punches, soon knocking him to the floor. "Knee to head," Raja exclaims as he enters the ring to hug the victorious fighter.
Raja is also behind what UK officials say is the most successful effort they have seen to de-radicalize some of the most hardline Islamist extremists being released from UK jails, including around a dozen convicted terrorists who recently completed their prison sentences.
He has used cage-fighting as a key tool in this work. Raja says teaching the former terrorists cage-fighting skills has proved a remarkably effective way of breaking them out of their al Qaeda mentality, opening up their minds to his counter-extremist message, and providing them with a sense of discipline and purpose.
Raja knows how to connect with his charges. Like several of them he is from the tough neighborhoods of east London, once subscribed to fundamentalist views himself, and Raja says he came close to fighting Jihad in Bosnia in the 1990s.
His life story shows the young men he is working with that they can transform their own lives by embracing a spiritual, humanistic, and tolerant Islam.
As a teenager Raja, by his own account, had run wild. He had at first lived in east London but after his father left the family when he was 11, he and his brother Suleiman were brought up on a public housing estate by his mother in Farnborough, a white working class town south west of London dominated by the presence of nearby military barracks.
As a single parent, she struggled to provide for them. Raja, as one of the only non-white kids in town, often suffered racial abuse. It started, he said, when he was about eight.
"One guy once asked me "has someone spread excrement on your face?" When I was 13 another guy came up to me and threatened to smash a milk bottle on my head," Raja said.
His response was to fight back. "The reaction was if I punch him in the face he tastes his own blood -- it's going to stop him being racist," Raja recalled.
His father came back into his life when he was 16. For a period he and his brother moved up to Huddersfield in northern England to live with him. "In order to civilize us he got us involved in Thai boxing," Raja said.
The 16-year-old Raja had quite an attitude but, he says, he soon got a reality check, which saw him learn the virtue of self-discipline.
"I remember in my third session my Thai boxing coach lifted his elbows, allowed me to kick him as hard as I could in the ribs while sparing, grabbed my head, kneed me in the head and broke my nose and that woke me up," Raja told CNN. From then on he trained six days a week. "Going into that reality makes you check yourself," he said.
At around the same time Raja became inquisitive about Islam for the first time. Though his mother prayed five times a day, religion had never been an important part of his life.
"I had looked at Islam and thought wait a minute, you've got a messed up religion where women have to cover their heads and stay at home, while men are out doing what they want," he recalled.
Like many born again into Islam with little exposure in their youth to Islamic teaching but a desire to deepen their faith, Raja gravitated towards Salafist-fundamentalism. "That's just what was out there," he said.
Salafism is a literalist approach to Islam that has taken on different forms across the Muslim world but followers seek a return to what they say are the true values of the religion before these were corrupted by Western modernity and other influences. While many Salafists are Amish-like in focusing all their energies on living their religion, a small but significant number, particularly in the West, have in past decades become politicized.
"It was all about Jihad in Afghanistan, Chechnya and Bosnia," Raja said. There was widespread anger in the Muslim community about the massacres of Muslims by Bosnian-Serbs in the Balkan country.
"I found myself feeling that injustice and wanting to go there and fight that injustice," Raja recalled.
"My dad was willing to fund that but the mosque committee stopped him," Raja said.
He channeled his energy into fight training, eventually becoming one of the UK's top cage-fighters. He attended a graphic design course at a college back in Farnborough and earned occasional money as a bouncer, but his priority was fighting.
"You start to glorify yourself," Raja recalled. "Over time you realize that ego is the biggest opponent."
The sport was fast taking root and its leading lights were beginning to become lionized like gladiators in Rome.
Many of his friends from fighting were white working class who in the early days made up the majority of the sport's fan base and fighters.
Many of them also lived hedonistic life styles: women, nightclubs, and cars. "Though I was a Salafist, it wasn't like I was puritanical," Raja said. "For me it was always more about the oppression of Muslims overseas than Sharia law."
His hand-combat skills also gave him street-cred with young British Salafists who were inspired by mujahideen exploits overseas.
Hardly any of the immigrants from Pakistan in his grandfather's generation had espoused Salafist views. After arriving in the UK, his grandfather founded one of the first mosques in east London, which espoused the tolerant, traditional Islam of his homeland.
"But then the Salafists came along, rolling up their trousers, criticizing jeans," said Raja.
The Millennium was approaching when Raja got what he calls his biggest wake up call. His grandfather fell gravely ill and he visited him in hospital in his final hours.
"He said his only regret in life was not providing more charity, kindness, and generosity to people. This was like a hammer blow to my head; he was the most kind, giving person I knew. His death made me think what are we here on earth to do?"
Raja was training in an east London boxing gym when he saw the twin towers collapse in Manhattan on a television monitor. One of his Muslim friends training next to him expressed little surprise given the rising anger against the United States in the Muslim world.
But for Raja what had happened was just plain wrong.
The death of his grandfather had slowly set in motion a change in his religious views. As he learned more about Islam, be became increasingly frustrated by what he saw as the hypocrisies and contradictions of Salafist teaching.
In 2003 he met a Malaysian religious teacher Sheikh Aleey Qadir, who had come to the UK in the 1990s to spread a spiritual interpretation of Islam.
Qadir's religious authority -- and that of several other preachers who developed a global following -- derived from being able to trace a lineage of learning, passed down from teacher to student that stretched back directly to the Prophet Mohammed.
They argued that because this unbroken line of knowledge predated the codification of the revelation into text, they had the authority to interpret its true essence.
And they rejected what they saw as the slavish anti-modernist literalism of Salafism in favor of Islam as a spiritual pathway, which they accepted was one of different ways, including other religions, to God.
"The message of my teacher was that humanity is all part of one body. If one part of the body is hurt we are all hurt - if one human is killed then we are all killed," Raja said.
This, Raja says, was the Islam he had always been searching for: tolerant, humanistic, open-minded, and one in which -- because he felt instinctively both British and Muslim -- he could feel comfortable.
Inspired by the Sheikh's message, Raja felt it was now his mission to help troubled youngsters salvage their lives by making them understand what he had.
In his late 20s Raja called time on his own fighting career and began trying to help others. In 2005, he carried out his first community outreach work with Kurdish Muslims involved in London's violent criminal underworld, whom he had encountered through his coaching in London gyms. "I had grown up with violence but I'd never seen anything like this," he said.
Raja says he came to learn their criminality originated from a "deviant Jihadist subculture" which he says has also been the most fundamental driver of terrorism in the UK.
He says that for too many young Muslims, religious hostility to the West, as well as encouraging terrorist plotting, has justified all manner of crimes, including theft, fraud and tax evasion. "For these Kurdish mafia guys, their Islamic service was their criminality. It was very odd to me at the time," Raja recalled.
His rehabilitation work with the Kurds led to him working to prevent youngsters from becoming radicalized by al Qaeda's ideology. At first he worked with a number of Muslim organizations involved in these efforts, but frustrated by their lack of impact and what he felt was their lack of understanding for the street, he decided to strike out alone.
One of the things Raja tried to confront was what he calls an "insular community mindset" and a "mono-culture" hostile to mainstream British values. Raja says he was particularly distressed by the widespread homophobia in the Muslim community.
As he describes it, the final piece of the puzzle was meeting his wife Kadija in 2008, a British-Indian Muslim convert, a recently qualified doctor, and the love of his life. She helped mellow him and re-order his priorities. "With Khadija you've got an example of a true Muslim woman," he says.
Together they founded the Unity Initiative in August 2009 and worked in tandem to rehabilitate some of the most hardened Islamist extremists emerging from British prisons by focusing on both the ex-convicts and their wives.
"Most people would probably not like to be in that situation but it the best thing that could have happened - he is my best friend," Khadija told CNN.
Usman and Kadija Raja's full integration into mainstream British community has provided a stepping stone for the former terrorist convicts they are working with to re-engage with society.
In July 2010 the Rajas attended the marriage ceremony of his long-time friend, celebrity cage-fighter Alex Reid to Katie Price, a British glamor model. It was a suitably extravagant affair. "My wife wore a hijab," Raja said, amused by the incongruity. "The fact that a friend of mind is a high profile fighter allows young Muslims at the street level to know that we are engaged in British society," Raja told CNN.
When the ex-con-terrorists come to his gym to train, they also mix with fighters who are mostly white working class, broadening their previously insular mindsets.
The Rajas still regularly turn to Sheikh Aleey Qadir for guidance, and the cleric often counsels the former terrorist prisoners they are working with.
"This isn't just a wishy-washy well-meaning community [initiative]. This is something that has been set up, that is supported by the world's foremost Islamic scholars," Raja told CNN.
"It is so exciting because we are actually seeing the results and there is change happening," said Khadija.
CNN's Ken Shiffman contributed to this report.