As investigators continue to search for possible accomplices in the Boston Marathon bombings, and clues as to how Tamerlan and Dzhokhar Tsarnaev were radicalized enough to commit violence, two writers say one mystery is obvious.

The embrace of a radical Islamist ideology was central to the attack, which mirrored plans spelled out in al-Qaida in the Arabian Peninsula's Inspire magazine, academic Jeffrey M. Bale and Muslim physician Qanta Ahmed write in separate columns.

"[T]hey had embraced a radical Islamist ideology that enjoined them to wage armed jihad against the 'infidel' enemies of Islam," writes Bale, director of the Monterey Terrorism Research and Education Program, in a column for the U.S. Naval Institute. "It hardly matters why the Tsarnaev brothers became disgruntled or angry—people can become disgruntled and angry for a vast array of both legitimate and delusional reasons. What matters is that this underlying emotional attitude made them receptive to and ultimately caused them to embrace Islamist doctrines, which offered them an explicit, coherent, and theologically sanctioned justification for perpetrating violence."

Ahmed, writing in the New York Post, agrees.

The narrative at the core of radical Islam is that violence is a necessity to "the idea of reclaiming a mythic Golden Age of Islam, a 'glory' that can be 'restored' only through violent jihad. Both their 'Islam' and the narrative are utterly fictional, yet the consequences of their make-believe are diabolically real."

The media often is reluctant to address this ideology, argues Bale, who has studied violent extremists for three decades. He criticizes "a blatant double standard" when violence is carried out by other extremists like neo-Nazis, white supremacists or anti-government groups.

"Nor do the media customarily refrain from noting the communist ideological agendas of left-wing terrorists, or the underlying beliefs fueling the violent actions of certain eco-radicals. Why, then," Bale asks, "is the role of Islamist ideology so often downplayed or denied in connection with acts of jihadist terrorism?"

By stifling the discussion, "we only shield the political Islamists," Ahmed writes, ignoring their often-lethal ambition to carry out attacks in the name of the faith. "Violent jihad is not a motive, but his sum raison d'etre. Without it, there can be no existence for the jihadist. Until he commits violent jihad, he doesn't truly exist — to feel real, he becomes a jihadist. And if he truly succeeds, his realized existence both births and extinguishes him simultaneously."

Bale and Ahmed have support from a former radical Islamist. "Jihadists who strike in America believe that by attacking the 'far enemy, — that is, the United States — they can weaken American resolve for supporting the 'near enemy', the rulers who stand in the way of a Middle Eastern jihadist superstate," Maajid Nawaz wrote in London's Sunday Times.

Those who argue other factors drove the Tsarnaevs to attack "are either being disingenuous or living in a state of psychological denial, if not in a parallel mental universe," Bale writes. Nawaz, who now works to counter the narrative he once embraced, said it's not enough to target the people plotting violence. The West also must defeat "the cause they espoused."