To look into this, we recently went to Great Britain, where there are more supporters of al Qaeda than anywhere else in the West.
In London we met a British Muslim, Maajid Nawaz, who told us that what is turning so many of his countrymen into radicals is something called the "narrative," that says the United States is out to destroy Islam.
It's an ideology Islamic radicals subscribe to.
We asked Nawaz, a former true believer: exactly what is the narrative?
Full Segment: Jihadists And "The Narrative"
Web Extra: What Is The Narrative
Web Extra: Bin Laden's Former Comrade-in-Arms
Web Extra: Weaning Himself from The Narrative
Web Extra: How The Brits Battle The Narrative
"That America is waging a war against Islam, invaded Iraq because it hates Muslims, invaded Afghanistan because it hates Muslims," he told "60 Minutes" correspondent Lesley Stahl. "And that the only way to stop this war is for Muslims to start fighting back on all fronts against the West."
Asked if he bought it all, Nawaz said, "Absolutely, yeah. I believed it."
"You accepted everything you were saying? There was no cynicism within you?" she asked.
"No, and I put my neck on the line for these beliefs. I was a genuine, committed ideologue," he replied.
Nawaz was a leader of Hizb ut-Tahrir, or Party of Liberation - one of Britain's most active Islamic extremist groups. He joined when he was in college at the University of London.
"This is where I actually took the oath, the membership oath," he recalled.
It is also where he recruited other students to fight against the West.
"Was it easy to recruit kids here? Were they susceptible? As you say, they're very intelligent, they're well-read," Stahl asked.
"It was very easy. And I've got to say, that actually intelligence makes it easier. And it's intelligent people that adopt ideologies," Nawaz said.
He points to people like the alleged Christmas Day bomber, who also attended the University of London; and the ring leader of the suicide bombing of the London Underground, who went to Leeds Metropolitan University.
In a martyrdom video, the ring leader of the London suicide bombing told the British public that by invading Iraq, the West demonstrated it was out to destroy Muslims.
"Your democratically elected governments continuously perpetuate atrocities against my people all over the world," he said in the video.
"And this is in a thick Yorkshire accent, someone who's born and raised in the U.K. saying to his own fellow countrymen, 'Your people have attacked my people.' What suddenly made him think that the British public had attacked his people, who are the Iraqi public, when he's a member of the British public, born and raised here?" Nawaz asked.
The ringleader of the London bombings is the picture of homegrown terrorism, with a biography similar to Maajid Nawaz.
A third generation Pakistani-Brit, Nawaz grew up in an upper-middle class home in Essex, east of London. His father was a successful engineer in the oil business and growing up, Nawaz was both happy and assimilated.
"All my friends were non-Muslims. I actually knew very little about Islam, like very little," Nawaz recalled.
He told Stahl he wasn't religious at the time and didn't go to mosque.
Everything began to change in his early teens, when he and his mostly white friends were attacked by racist gangs.
According to Nawaz, they were skinheads. "They didn't attack me directly. But they attacked my white friends in front of my eyes to discipline them, to make examples of them for being blood traitors," he told Stahl.
"Just by being your friend, they were 'blood traitors"? Stahl asked.
"Yeah," Nawaz replied.
"So, you'd be out with your white friends and the skinheads attacked them, not you?" she asked.
"They would hold me back and force me to watch them stab my friends…with knives. I was about 13, 14 years old," Nawaz remembered.