A growing body of psychological literature suggests that suicide bombers aren't ideologues who are so committed to their cause that they're willing to die for it — rather, they are suicidally depressed people who use the excuse of dying for a cause to psych themselves up to commit the deed, and as a loophole for committing suicide without committing a sin.

Lankford's forthcoming study, to be published early next year, is "far more robust" than his first: a list of more than 75 suicide terrorists and why they were likely suicidal. He cites a Palestinian woman who, five months after lighting herself on fire in her parents' kitchen, attempted a return to the hospital that saved her life. But this time she approached with a pack of bombs wrapped around her body, working as an "ideologue" in the service of the al-Aqsa Martyrs Brigade.

Lankford writes of al Qaeda-backed terrorists in Iraq who would target and rape local women, and then see to it that the victims were sent to Samira Ahmed Jassim. Jassim would convince these traumatized women that the only way to escape public scorn was martyrdom. She was so successful she became known as the Mother of Believers. "If you just needed true believers, you wouldn't need them to be raped first," Lankford said in an interview.

Lankford is also intrigued by the man who in some sense launched the current study of suicide terrorism: Mohammed Atta, the ringleader behind the 9/11 hijacking. "It's overwhelming, his traits of suicidality," Lankford said. An isolated, neglected childhood, pathologically ashamed of any sexual expression. "According to the National Institute of Mental Health there are 11 signs, 11 traits and symptoms for a man being depressed," Lankford said. "Atta exhibited eight of them."