This column has been updated.

NASCAR’s original report that a noose had been found in Bubba Wallace’s garage doesn’t change its doomed relationship with the old rebel South. It’s over. The stock-car drivers who marched on the track Monday at Talladega Superspeedway had a certainty in their step that felt momentous. They weren’t just walking with Wallace. They were walking away from something: a past.

Kyle Busch was there, and Kevin Harvick, and team owner Richard Petty was, too, right alongside the No. 43 car in a gesture of brotherhood over what they all believed was a hate crime. Maybe they were all oversensitive, too much on edge, when they immediately believed the report that someone had hung a lynching rope in Wallace’s garage. It suggests just how much tension NASCAR is experiencing over its decision to ban the Confederate flag from its tracks, and exactly what kind of nasty blowback it expects.

NASCAR’s casual acceptance of that flag is over. But this promises to be a long fight with a certain hard base of its audience, and perhaps with some insiders, too. Understand this: That flag isn’t going away. As John M. Coski writes in his book “The Confederate Battle Flag: America’s Most Embattled Emblem,” it’s not “an alien symbol grafted onto the American tradition and is not therefore simply going to disappear. The people who fly or revere the flag will not become extinct, and they will resist efforts to reeducate them to view it as offensive.”

The question of why so many people wave it so tenaciously is not easily answered. It has become associated with multiple meanings, some of which are difficult to uproot. To one segment, it represents the “defense of constitutional liberty against Big Government,” Coski suggests. For others, the soldierly valor of an ancestor. Such people “resent the categorical denunciation of it as only a symbol of slavery and racism,” he observes. That resentment probably will only be heightened by the categorical denunciations that came with that mistake in Wallace’s garage.

Nevertheless, NASCAR was utterly right to make those denunciations, and to dissociate itself from that flag as a way of repudiating its racist past. You can’t separate the battle flag from its original cause, pull blameless threads from it or sew milder meanings into it.

Drivers have a long road ahead to make this understood to their Dixie fans, but that’s as much an opportunity as a problem. Seldom has a sports league had the chance to reach an audience with a bolt of truth, and change common perceptions of a cultural article, as NASCAR’s drivers do now. With their inimitable combination of intelligence, common touch and Southern roots, they are better suited than anyone to explain why that flag is an unfit companion at events that fly the stars and stripes.

Southerners may think they know everything about that flag, but too many of them don’t know the half of it. The hothead sovereigns of the Confederate states actually cycled through three different banners over the course of the war to symbolize what they fought for. For a time, they used something called the “stainless banner.” It had the Southern cross on a large field of white — and that white meant exactly what you might suppose it did.

“As a people, we are fighting to maintain the heaven-ordained supremacy of the white man over the inferior or colored race,” the Savannah Daily Morning News wrote. “A white flag would thus be emblematical of our cause.”

The problem was that it was impossible to keep that white flag clean. Jimmie Johnson should tell that story to his fans every time he gets the chance.

There is no innocent thread in that flag: It was the battle standard of Robert E. Lee’s Virginia troops engaged in a malevolent racism that rent the country in two, the pennant of an old slave driver who chose to fight for plantation over country.

Next time Denny Hamlin has a news conference, he should turn it into a lively discussion of which side was really fighting a war of “aggression.” He should quote what men such as Jefferson Davis and Robert Barnwell Rhett really said about the expanding empire they envisioned, which included annexing tropical territories to extend slavery into Cuba, Jamaica, South America. Rhett boasted of building “a great Slaveholding Confederacy, stretching its arms over a territory larger than any power in Europe possesses.” There’s your so-called war of “Northern aggression.”

Sentimental clinging to the Confederate flag by sports audiences has as much to do, I suspect, with fear as racism. It has to do with a reluctance to face the potentially unbearable revelation. As W.E.B. Du Bois wrote in his classic 1935 work, “Black Reconstruction in America,” so much of the Civil War retellings are “cajoling and flattering the South and slurring the North.” The South must be flattered and the North slurred, because otherwise what you are left with is the simple fact that some Americans made monstrously wrong, immoral choices. The easiest way to cover that up is to wave an old flag and say they were just nice Southern boys doing their duty for their home soil.

To which Du Bois says: “This may be fine romance, but it is not science. It may be inspiring, but it is certainly not the truth. And beyond this it is dangerous … and it is helping to range mankind in ranks of mutual hatred and contempt, at the summons of a cheap and false myth.”

What if America isn’t what you thought it was? That’s the fear you face by pausing to read a little more deeply about that flag. What NASCAR drivers can do, the invaluable service they can perform for their audience, is to explain that authentic American history is invariably better than the cheap and false myth. “Learning some history is the only way to know who we are, how we got here, where we might be going,” author David Blight has said.

The reader who braves the experience will be comforted, not distressed. All the magnificent and moving values you hoped for are embodied there. Just maybe in different, more surprising places.

Places such as the account books of poet Henry Wadsworth Longfellow, who helped finance the escapes of fugitive slaves. Or the graduation rolls of Harvard’s Class of 1861, 68 percent of which volunteered to fight for the Union: The best-educated young elites of the North, with the first shot fired, decided to forgo ease and suffered a 30 percent combat casualty rate for it. Why don’t we talk more about their devotion to duty? Why don’t we replicate the flag of the 20th Massachusetts Regiment in souvenir shops?

The courage and the crime of the Confederate battle flag are inseparable. It’s long past time that NASCAR turned its back on that banner and all of its other old racist associations, from the hand-glove partnership with George Wallace to the segregation of Darlington. If you think that walk with Bubba Wallace was a small or mistaken matter, well, look at how long it took. It was a giant step.