Among those who identify with the “incel” movement, there is a pathological fixation on sex and women, and there is a self-pitying perception that everyone else, except the community of “incels,” is having sex. Women are craved, but they are also reviled for what the incels believe is their selective promiscuity: They seem to be having sex with everyone but them. This is internalized as a grave personal insult. The function of the “incel” movement is to transform that personal grievance into an ideology that casts women as despicable sexual objects.

The core emotion that animates “incels” is sexual shame. It’s not just that these men are sexually frustrated; it’s that they are ashamed of their sexual failure. At the same time, they are resentful of the sexual success of others, which amplifies their own sense of inadequacy. This explains why they gravitate toward an online subculture that strives to rationalize their shame and redirect the blame for their failure onto women.

Like incels, jihadists similarly crave sex, but the circumstances surrounding its consummation are closely regulated by their religious norms, which prohibit sex outside of marriage and same-sex couplings. Among jihadists, even masturbation is frowned upon, although Osama bin Laden famously issued a masturbation fatwa, permitting it in times of urgent need.

This repressive attitude toward sex and sexuality has led some commentators to suggest a connection between sexual frustration and the murderous rage of jihadist suicide bombers. The evolutionary biologist and atheist Richard Dawkins, for example, suggested that far from being motivated by thoughts of injustice, the Sept. 11 hijackers were driven by thoughts of sex. Referring to the “martyr’s reward of 72 virgin brides,” he asserted that “testosterone-sodden young men too unattractive to get a woman in this world might be desperate enough to go for 72 private virgins in the next.” Developing this theme further, the late Christopher Hitchens wrote that the jihadists’ “problem is not so much that they desire virgins as that they are virgins.” Or as the sociologist Mark Juergensmeyer once put it: “Can’t get married, can’t have sex, so they blow things up.”

It’s easy to dismiss these observations as reductive caricatures in their portrayal of Muslims as sexually repressed. And, of course, jihadist violence is about far more than just sexual frustration. But there is too much anecdotal evidence about the sexual torment of jihadists and their ideologues to reject the connection outright. For example, Sayyid Qutb, the grandfather of jihadist ideology, was disgusted by Americans’ sexual license during the 1950s, yet he was clearly viscerally excited by its spectacle. Mohammed Atta, the leader of the Sept. 11 hijackers, instructed in his will that his body be prepared for burial by “good Muslims” and that no woman was to go near it, presumably because he found them dirty and spiritually contaminating. This aversion to women didn’t stop him from visiting a strip club just before the attack, but it did prevent him from shaking women’s hands. One extremist reportedly told the terrorism scholar Jessica Stern that he was “vaginally defeated.”