The following is a script of "Recruiting for ISIS" which aired on Nov. 2, 2014, and was rebroadcast on June 14, 2015. Clarissa Ward is the correspondent. Randall Joyce, producer.
One of the most shocking things about the rise of ISIS in Iraq and Syria has been the thousands of Westerners who have given up everything to travel to a bloody battlefield far from home and live under strict Islamic Sharia law. But to understand the mentality of these jihadis, you don't need to travel to the Middle East. Across the West, ISIS has a committed support base that is actively recruiting young Muslims.
Back in October, we sought out a man at the heart of that movement, a British preacher who sees no border between the streets of London and the front lines of the Middle East. Talking to him and his followers gave us a window into a world you may find disturbing and difficult to understand.
There are at least 500 U.K. citizens fighting in Syria and Iraq and every week, according to British police, another five recruits join the fight.
British jihadis have been on the front lines with ISIS from the very beginning. In the group's recent videos showing the executions of Western hostages, the masked man holding the knife speaks with a London accent.
The spike in Western fighters may be in part due to this man, Anjem Choudary, a British-born lawyer turned Islamic preacher, who lives in London and has for years been asserting his democratic right to call for an end to democracy.
Anjem Choudary: I believe Islam is superior. And will not be surpassed. So I believe that the law of God is much superior to man-made law.
Clarissa Ward: So, in that sense, you believe that Islam and democracy are mutually exclusive? That they can't exist side-by-side?
Anjem Choudary: Allah is the only one to legislate. So, obviously, in that sense it's completely, diametrically opposed. You cannot have man legislating and playing God in Parliament, and at the same time believe that Allah is the only legislator.
Clarissa Ward: You have the freedom to come here today. You have the freedom to speak on television, to worship whichever God you please. But you're advocating a system that essentially would take away all of those freedoms?
Anjem Choudary: Allah created my tongue to speak. I don't have freedom to come here, because Allah created my feet to walk. So I walk, and I speak, and I look, and I hear according to what God says.
Choudary has been accused of inspiring hundreds of Muslims from across the West to join ISIS. We went to a meeting he held in an East London basement. On the wall was a large picture of Buckingham Palace turned into a mosque. He described the newly formed Islamic state in Iraq and Syria as a kind of utopia. Talking about jihad, he sounded at times like a coach giving a pep talk before the big game.
[Anjem Choudary: When the heavens are with you, when the earth is with you, when the sea is with you, when the wind is with you. Who's going to defeat you after that? Nobody.]
Choudary has fronted a series of organizations that have been banned by the British government under the country's anti-terror laws, but he denies that he actively recruits fighters.
Anjem Choudary: You know, the messenger Mohammad, he said, "Fight them with your wealth, with your body, with your tongue." So, I'm engaged here, if you like, in a verbal jihad.
Clarissa Ward: But what you're actually doing essentially is inspiring young men to go and fight in these countries, while you stay here and enjoy a comfortable life...
Anjem Choudary: No, I mean...
Clarissa Ward: ...in the United Kingdom.
Anjem Choudary: ...this is a kind of, the rhetoric that the Western media come out with. But, I mean, there are no examples of anyone, in fact, who is in any of the battle fronts, who actually say, "Well, actually, Mr. Choudary asked me to come here." Or, "He bought my ticket." You know? If it were the case...
Clarissa Ward: They wouldn't say that you bought...
Anjem Choudary: ...if it were the case...
Clarissa Ward: ...their ticket.
Anjem Choudary: Well, no if it were the case...
Clarissa Ward: But they might say that you inspired them with your message.
Anjem Choudary: There was a report out recently which said that I inspired 500 people, in fact, to carry out operations here and abroad. And if that were really the case, don't you think that I'd arrested be? And I'll be sitting in prison.
Clarissa Ward: So if a young man, one of your students, comes to you and says, "Should I go and fight in Syria or Iraq," what would you tell them?
Anjem Choudary: Well, they haven't come to me. And if they come to me I'll think about a suitable response. But I'm engaged...
Clarissa Ward: What would you tell them?
Anjem Choudary: I don't deal with hypotheticals.
Clarissa Ward: It's a hypothetical question.
Anjem Choudary: I don't deal with hypotheticals. I deal with reality. You know, I mean, there are many things that could happen, hypothetically. Young men come to me...
Clarissa Ward: Why won't you answer the question?
Anjem Choudary: Because it's a...
Clarissa Ward: It really should be an easy question.
Anjem Choudary: I like to deal with reality. If that happens, you can have another interview with me, and I'll deal with it.
But one week after our interview, Choudary was arrested "on suspicion of being a member of a proscribed or banned organization... and encouraging terrorism." Also rounded up in the raids, was one of his young followers, Abu Rumaysah.
[Abu Rumaysah: We want Islam. We want Islam to dominate the world.]
Talking to Rumaysah, you come face to face with a version of Islam that wipes out every other aspect of a person's identity. He is a convert from Hinduism but his new beliefs bar even the most basic human feelings towards his mother and other family members who didn't convert.
Abu Rumaysah: I don't love them as non-Muslims, but I desire for them to become Muslim and embrace Islam.
Clarissa Ward: But you love her as your mother?
Abu Rumaysah: She's my mother and she has rights over me, so I have to take care of her. I have to look after her. I have to make sure that, you know, she's protected and secure. So I fulfill my obligations like that.
Clarissa Ward: But do you feel love for her?
Abu Rumaysah: It's not allowed for me to love non-Muslims. So that's something that is a matter of faith.
Clarissa Ward: So do you feel that you are British?
Abu Rumaysah: I identify myself as a Muslim. If I was born in a stable, you know, I'm not going to be a horse. If was born in Nazi Germany, I'm not going to be a Nazi. I mean, this is just an island I was born in.
Rumaysah and Choudary both live in east London, which is home to one of the largest Muslim populations in the U.K. In one part of town, Rumaysah and his associates have set up so called "Sharia patrols" to go out and discourage behavior that they deem un-Islamic.
On this night they stopped to talk to a couple of non-Muslim men who were in a park drinking beer, which is forbidden under Islam.
[Male voice: So we're just reminding anyway. Reminding the community about staying safe. And in this area there's a lot of gambling that goes on. A lot of alcohol drinking and it leads to a lot of problems. So we advise you and we advise anyone we see to stay away from these things.]
But the patrols are not always so friendly. Online clips give a very different picture.
A woman in a short skirt is abused. A man the patrol thinks is gay is insulted.
Walking through London with Rumaysah you experience an alternate reality where there is no compromise and all conversations are one sided.
Abu Rumaysah: Ultimately, I want to see every single woman in this country covered from head to toe. I want to the see the hand of the thief cut. I want to see adulterers stoned to death. I want to see Sharia law in Europe. And I want to see it in America as well. I believe our patrols are a means to an end.
Clarissa Ward: The only thing I would say is that in America and in the United Kingdom, we have a system: democracy.
Abu Rumaysah: A backwards one.
Clarissa Ward: But it's a system...
Abu Rumaysah: A barbaric one.
Clarissa Ward: ...that allows the people to choose what they want and allows people freedom.
Abu Rumaysah: So why can't I choose Sharia? When in Rome, overthrow Caesar and commit to Sharia.
Clarissa Ward: In your home, you can do whatever you want?
Abu Rumaysah: But what about in the public? Why can't I tell you to cover up? Am I free to say that?
Clarissa Ward: Because it would be outrageous. Of course, you're not...
Abu Rumaysah: So where's my freedom? Where's my freedom?
Clarissa Ward: You can say it to me, but you...
Abu Rumaysah: Okay. So cover up. Wear the hijab.
Clarissa Ward: That's absurd.
The thought of Choudary's supporters taking the law into their own hands is deeply frightening to most British people. This is a group that believes the West is at war with Islam. And that the invasions of Iraq and Afghanistan justify any kind of violence in response.
The most shocking example of that logic was the gruesome and very public murder of British soldier Lee Rigby on a London street in 2013. On that day the man wielding the knife was a known associate of Choudary.
Choudary has refused to condemn Rigby's murder. Nor will he criticize ISIS for the beheading of American journalist James Foley and other Western hostages.
Anjem Choudary: You know, I don't know the details about James Foley, but...
Clarissa Ward: I know the details. Let me educate you, because he was a friend of mine.
Anjem Choudary: I don't believe you. I'm sorry, I don't believe you.
Clarissa Ward: You don't believe me that...
Anjem Choudary: The fact...
Clarissa Ward: ...James Foley was a journalist?
Anjem Choudary: I don't believe. No, I don't believe any Western journalists, quite frankly. I believe you're liars until proven otherwise. But let me tell you something, the perspective of the Muslims of journalists, whether that be James Foley and others, is that they are the propaganda for the Western regimes.
Clarissa Ward: Have you formed an opinion for yourself?
Anjem Choudary: I form my opinion on the basis of what the Muslims say, not on the basis of what you say.
Clarissa Ward: I'm sensing a double standard here. Because essentially you're very quick to condemn acts of violence by the West. But you refuse to condemn any act of violence by your fellow Muslims.
Anjem Choudary: No, I believe that there's a difference between the oppressor and oppressed.
Britain's authorities have struggled with how to handle extremists like Choudary and his followers. He has been arrested multiple times but never convicted of anything more than staging an illegal demonstration.
And now the police face a new challenge that is nearly impossible to manage: the spread of Islamic extremism through slickly produced online propaganda films from real fighters in real battlefields.
[British jihadi: We will chop off the heads of the Americans, chop off the heads of the French, chop off the heads of whoever you may bring.]
Those videos have proven wildly attractive to thousands of young people who feel alienated from the Western societies they live in. For them, jihad offers the promise of power and glory.
Sir Peter Fahy is in charge of a government program called "Prevent," set up to combat the radicalization of British Muslims.
Sir Peter Fahy: I think the big concern about the current situation is just a huge amount of material which is available on social media, in the various publications and the various videos that I think a lot of us are struggling to come to terms with and get a good picture of.
Clarissa Ward: So in a sense, it's less about preachers radicalizing young men. And it's more young fighters radicalizing other young fighters from the battlefield using social media as their recruitment platform?
Sir Peter Fahy: I think you're absolutely right. That is my concern is that what has changed again over recent months is that you have got local people identifiable as real people. You've got, you know, a person who's identifiably British who's gone out there and is absolutely using social media to be able to communicate directly into your son or daughter's bedroom and to encourage them to come out. And I think that is extremely worrying as a new development. As I say, I think a lot of families and a lot of parents, including obviously Muslim parents, are very concerned about that.
Clarissa Ward: Bedroom jihad, they're calling it.
Sir Peter Fahy: Absolutely. It's almost that personal contact which is the worrying aspect. But, you know, we need to be aware of all different forms of brainwashing and radicalization.
Clarissa Ward: If their parents can't stop it, what can you do to stop it?
Sir Peter Fahy: Well, all we can do is raise awareness. But you're absolutely right. And we constantly agonize about whether this is a job for the police or not.
Britain's mainstream Muslim leaders are speaking out against ISIS and have discouraged young men in their communities from joining the fight. But the ongoing U.S.-led military campaign in Syria and Iraq has stoked anger and raised fears of terrorist retaliation attacks in the West.
Clarissa Ward: Do you believe that there will be more attacks in the West?
Anjem Choudary: Yes. I believe it's inevitable.
Clarissa Ward: If you believe that, would you ever use your role as a British citizen, and as a Muslim, to actively dissuade people from launching attacks here in the U.K., in the U.S., in the West?
Anjem Choudary: Well, I think we need to deal with the root causes. I think it's really absurd to say, "Well, why shouldn't people react?" The fact is if we don't deal with the root cause, which is the occupation of the Muslim land, which is the torture of Muslims, which is the foreign policy of governments like Britain and America, that you will never be able to stop people.
Clarissa Ward: So, just so I understand, you will continue to refuse to condemn acts of terror?
Anjem Choudary: Well, as I say, you know, I'm not in the game of condemnation or condoning.
Clarissa Ward: It's really just a yes-or-no question.
Anjem Choudary: Well, I don't want to answer you with a yes-or-no answer.
It's not yet known whether Choudary will ever have to give straight answers in a courtroom. His bail has been extended through August but so far no charges have been filed.
In the weeks after our story first aired, we found out that Abu Rumaysah, the young convert from Hinduism, skipped bail and fled the UK for Syria. He is now living with his wife and children in ISIS territory.