No liberal society could foresee the moment when true believers were going to give in to their derangement.
Islam had put down roots in Britain. This was the backwash of empire. When the British empire pulled back from its far-flung dominions, its Muslim subjects followed.
The growth in their ranks was phenomenal: There were 23,000 British Muslims in 1951, 369,000 in 1971, 690,000 in 1981 and 1.6 million by 2001.
Mosques multiplied: 10 in 1945, 329 in 1989, 1,493 by 2003.
Radical preachers who quit the secular dictatorships of the Arab world made their way to London. There was freedom in London, and there were state welfare subsidies.
The preacher who now claims to have inducted Adebolajo to the ways of radical Islamism was a notorious bigot, Omar Bakri Mohammed, a man of Syrian birth, who gathered around him a group of bewildered, angry young men, Al Muhajiroun (the Emigrants).
London gave Bakri all he could aspire for: welfare relief, followers, a soapbox.
He hailed the Sept. 11 attacks, and described the death pilots who struck America as the "magnificent 19." Lawyers sheltered him from deportation.
His luck ran out in 2005 when the authorities blocked his return to London after a visit to Lebanon. He gave his sanction and approval to the killing in Woolwich. He justified it on the grounds that the victim was a man of the military and not a civilian.
Britain's moment of grief at the hands of radical Islamists, its 9/11, came in 2005 with the 7/7 attacks. London's transportation system was struck by four jihadists and 52 people were killed.
A parliamentary report later laid bare the world of these younger men who bore British society a dreadful hatred.
Three of the bombers had been born in West Yorkshire. The fourth was a Jamaican-born convert to Islam who was a "bright child, successful academically, at school, and good at sport." The oldest of the four, age 30, with a 14-month-old child, was considered a role model for younger people.
One of the four, Shehzad Tanweer, 22, was particularly privileged.
He led, by all appearances, a "balanced life," the investigative report said. He owned a new Mercedes, given to him by his father, and was fond of fashionable hairstyles and designer clothes. Tanweer played cricket the night before the bombing.
On the day of the horrors, a surveillance camera filmed him in a store: "He buys snacks, quibbles with the cashier over his change, looks directly at the CCTV camera and leaves," according to the report.
Naturally, al-Qaeda's leaders claimed the bombers. Yet one suspects they are the children of a more tangled trail, at once so familiar and so unrecognizable.
Ajami is a senior fellow at the Stanford University's Hoover Institution and author, most recently, of "The Syrian Rebellion." His column is distributed by Bloomberg Views.