A decade on, everything had changed. I had witnessed 9/11 from Riyadh. I had written a book about my time in Saudi Arabia, In the Land of Invisible Women: A Female Doctor's Journey in the Saudi Kingdom, and I was confronting radical Islamism through my journalism. In 2010, having moved to New York to continue my medical career, I received a familiar-sounding invitation. Attorney Richard Horowitz, an internationally recognised authority on terrorism who shared my concern about radical Islamist terrorism, wanted to know if I'd join him in his office to view some homemade jihadist recruitment videos. This time I didn't refuse.

Exchanging Chop-Chop Square for Times Square, where Horowitz was based, we watched a rare series of grainy films. They transported us from New York to the Afghanistan-Pakistan border. For long minutes, we watched a Muslim boy, who looked barely 12, decapitate a Muslim man with a blunt knife, struggling to sever each and every strap muscle, cartilage and vertebra that secured the head to the torso. The finale accomplished, the blood-spattered boy in too-big sneakers was lionised, roundly praised in the language of my faith. Hundreds watched with admiration.

It was a pivotal experience, and I knew I needed to know more about the people who committed these acts in the name of my faith. By 2012, I was meeting Pakistani child jihadists in Malakand, in north-west Pakistan. Boys groomed to be suicide bombers, Taliban operatives and Taliban informers, boys who might have been in videos like the ones I had seen, told me in the unschooled Urdu of the Swat Valley about their own paths to jihadism (journeys I have recounted in testimony on Capitol Hill).

In recent weeks, I have watched in stunned horror as the Western world struggled to come to terms with the brutal decapitation of American journalist James Foley (pictured), followed just two weeks later with that of Steven Sotloff. But unlike many westerners, I am all too aware of the fact that such barbaric punishment is far from unusual. In a recent conversation, Horowitz summed up the situation with these bleak words: "Decapitations are now mainstream."

As a devout Muslim, the tragedies of recent days have packed an added blow for me. Along with the senseless loss of two promising young lives, I have been forced to confront the fact that the beautiful religion that continues to sustain me – that supports me in my life-giving work as a physician – is increasingly the domain of those who would use it to destroy everything I hold dear.