The Islamic State Caliphate has begun the destruction of the glorious archaeological site of Palmyra in central Syria, where the Roman Empire met the East and a fusion culture formed. The fanatics already had leveled numerous ancient monuments, irreplaceable wonders of humanity’s common heritage. And those rampages came atop the systematic destruction of 2,000 years of Christian civilization in the Middle East, accompanied by massacres of members of every local faith, including Islam.

And what outrages the American Left? The horrific destruction? The breathtaking slaughter? No. Our Left has gone to the barricades over the prospect of a Southern working stiff putting a Confederate Battle Flag decal on his pickup truck.

I’ve always hoped that at least some of the Left’s stirring rhetoric about human dignity and culture was sincere, but my hope has become considerably less audacious. How can the Left look away from the comprehensive destruction and atrocities perpetrated by the Islamic State? Do brown lives matter only when deaths can be blamed on American drones? Where are the “Hands up! Don’t Decapitate!” demonstrations?

And if leftists truly don’t care about the hundreds of thousands slaughtered by regional factions (the Islamic State being only the most imaginative), don’t our self-appointed arbiters of culture – ever so quick to ridicule the rest of us as rubes – care about the obliteration of ancient treasures that rival the Parthenon or Roman Forum?

I was trying to crack this riddle on my way to the Fox studio – and the light went off at a traffic stop, literally and figuratively:

For all of their profound differences, the Islamic State and the Left have one purpose in common: They want to wipe out history so they can write it anew to support their utopias, the perfected societies of their inhuman fantasies.

The Islamic State destroys wondrous monuments to prevent “pagan worship,” to purify Islam and restore the caliphate to a state of perfection it never possessed. Aiming at a less puritanical, if equally rule-bound utopia, the American Left has all but destroyed the teaching of history in our schools, scorning facts in favor of paternalistic condescension toward minorities.

Thus it’s not enough to take the reasonable step of removing the Confederate Battle Flag from state and local government properties. That flag must be driven from the marketplace, from all public spaces and, at last, from the personal space, since it might be “hurtful,” even if hung in a basement. It’s admirable to celebrate the Black Panthers, but not for a struggling working man to honor a Civil War ancestor. In this case, brothers and sisters, bigotry ain’t a monopoly.

Islamist State sledgehammers smash off the faces of classical-era statues. Our Left wants to remove Founding Fathers and others from our currency to replace them with minor figures that suit their agenda. Both actions are about mastering the past to control the future.

 (Might I suggest a compromise on the currency issue? The Left can put anyone it wants on the 20-dollar bill, if our high-school textbooks can teach that the Democratic Party was the party of slavery, the KKK, Jim Crow and segregation into the 1960s – and remains the party obstructing quality education in inner cities.)

And our Left and the caliphate share still more common ground on their routes to utopia: the Islamic State has drawn from the Left in its jihad against the past. When socialism first infected the Middle East, it deteriorated rapidly into steel-fisted statism. And the Saddam Husseins and Assads took a crucial lesson from Stalin and Mao: They did all they could to erase the memory of inconvenient individuals and disturbing facts. The Islamic State got the memo.

One of the Left’s major contributions to humanity has been to render “truth” endlessly malleable (“If you like your doctor, you can keep him”).

The Islamic State wants to obliterate the glories of the past, in service to humanity. The global Left denies the greatness of Western Civilization, in service to humanity. Their methods differ, but their utopian goals are equally divorced from tolerance, from all allowance for human frailty and, not least, from mercy.

When that amnesiac utopia arrives, whether in the wreckage of the Middle East or on our soil, the one thing of which we may be certain is that human beings will not prove perfectible. And heretics and apostates, the “enemies of the people,” must be destroyed.

Allah and Stalin will it.

Fox News Strategic Analyst Ralph Peters is a retired U.S. Army officer and former enlisted man. He is the author of prize-winning fiction and non-fiction books on the Civil War and the military. His latest is "The Damned of Petersburg: A Novel" (Forge Books, June 28, 2016).