Mona El-Naggar reports: He winced at the mere mention of his son’s name, visibly overcome by an unceasing thought that he struggled to articulate. He looked down to hide the tears in his eyes.

“You have to understand, I am in pain,” said Yaken Aly, choking on the words: “My son is gone.”

Mr. Aly raised his son, Islam Yaken, in Heliopolis, a middle-class Cairo neighborhood with tended gardens and trendy coffee shops, and sent him to a private school, where he studied in French. As a young man, Mr. Yaken wanted to be a fitness instructor. He trained relentlessly, hoping that his effort would bring him success, girlfriends and wealth. But his goals never materialized. He left that life and found religion, extremism and, ultimately, his way into a photograph where he knelt beside a decapitated corpse on the killing fields of Syria, smiling.

“Surely, the holiday won’t be complete without a picture with one of the dogs’ corpses,” Mr. Yaken, now 22 and fighting for the Islamic State, also known as ISIS or ISIL, wrote in a Twitter post in July, during Ramadan.

The West is struggling to confront the rise of Islamic extremism and the brutality committed in the name of religion. But it is not alone in trying to understand how this has happened — why young men raised in homes that would never condone violence, let alone coldblooded murder, are joining the Islamic State and Al Qaeda. It is a phenomenon that is as much a threat to Muslim nations as to the West, if not more so, as thousands of young men volunteer as foot soldiers, ready to kill and willing to die. [Continue reading…]