"A mass movement," wrote Eric Hoffer in "The True Believer," "appeals not to those intent on bolstering and advancing a cherished self, but to those who crave to be rid of an unwanted self.

"Their innermost craving is for a new life—a rebirth—or, failing this, a chance to acquire new elements of pride, confidence, hope, a sense of purpose, and worth by an identification with a holy cause."

Such a man was Michael Zehaf-Bibeau, a criminal with a decade-long record of drug-dealing, assault and robbery, who shot and killed a guard at Ottawa's National War Memorial and then burst into Parliament and shot two others before being cut down.

A psychiatric evaluation of Zehaf-Bibeau in 2011 found, "He has been a devoted Muslim for seven years, and he believes he must spend time in jail as a sacrifice to pay for his mistakes in the past."

Now Zehaf-Bibeau is known to his countrymen and the world. Now his deeds are celebrated by the Islamic State he sought to join.

To understand the appeal to such men of the Islamic State, despite its cruelties, beheadings, crucifixions, slaughter of prisoners, rape and sale into slavery of the daughters and wives of enemies, there are few better sources than the longshoreman-philosopher Eric Hoffer.

Why do young men and women travel from a free prosperous West to fight in Syria and perhaps die in a suicide bombing? What do they seek?

What does ISIS offer? And a more alarming question—why do these jihadists and terrorists continue to gain ground and attract new recruits?

Bin Laden may be dead, but he is world famous and by no means universally loathed for slaughtering 3,000 Americans. During the Bush era, he was more popular in the Muslim world than the U.S. president.

Al-Qaida may have been obliterated in Afghanistan, but has spread to Pakistan, Iraq, Syria, Libya and Yemen, spawning imitators, like ISIS, from the Maghreb across the Middle East into black Africa.

Why are almost all the suicide bombers, the martyrs, on their side?

Wrote Hoffer:

"All mass movements generate in their adherents a readiness to die and a proclivity for united action. ... All of them irrespective of the doctrine they preach and the program they project breed fanaticism, enthusiasm, fervent hope, hatred and intolerance; all ... demand blind faith and singlehearted allegiance."

Does this not fairly describe the Islamic State?

Still, what does ISIS offer the young?

A second chance at a heroic life. A cause to die for. A vision of a new world as Allah intended it. Communion and camaraderie. And should one die striking a blow against the infidel, there is martyrdom and a place of honor and happiness in the world to come.

To the True Believer, writes Hoffer,

"Chaos is his element. When the old order begins to crack, he wades in with all his might to blow the whole hated present to high heaven. ... He alone knows the innermost craving of the masses in action, the craving for communion, for the mustering of the host, for the dissolution of cursed individualism in the zest and grandeur of a mighty whole. Posterity is king."

Another attraction of the Islamic State is that it appears to be not only the strongest of the jihadist movements but also the most feared by America.

An indispensable aspect of mass movements is hatred, writes Hoffer. Mass movements can never rise and spread "without a devil."

Indeed, he adds, "the strength of a mass movement is proportionate to the vividness and tangibility of its devil ... the ideal devil is omnipotent and omnipresent. ... The ideal devil is a foreigner."

Superpower America fits the bill perfectly, assuming the devil role by intervening in the war against the Islamic State in Iraq and Syria. Our presence in their war testifies to the truth of what their leaders preach: We are the ones America fears most.

In a West saturated in self-indulgence, to many young Muslims, this must have an appeal. Again, Hoffer: "There is no doubt but that in exchanging a self-centered for a selfless life we gain enormously in self-esteem. The vanity of the selfless, even those who practice utmost humility, is boundless."

The Islamic State cannot defeat the United States. But in fighting against the United States, ISIS sends a message to an Arab and Islamic world where we are not loved that they are the enemies we fear most.

If you wish to fight the Great Satan, come join us.

Thus, while we are killing them, we recruit for them.

Moreover, in waging war against ISIS in Iraq and Syria, we are not only sheltering the Shia Crescent of Iran and Hezbollah, we are fighting a Sunni war that Sunni powers like Turkey refuse to fight for themselves.

We are now on both sides of the Sunni-Shia sectarian struggle that has never been America's war, and we have no credible strategy and no credible army to win it. Who got us into this?