We were driving up Interstate 81 last Sunday afternoon, the radio on, the sun setting into the hills, when we passed a tractor-trailer truck, and saw Old Glory proudly snapping in the strong wind behind the cab.

Twenty-four hours after an avowed white supremacist, terrorist and accused murderer named James Alex Fields Jr. allegedly plowed his car into a knot of protesters in Charlottesville, Virginia, killing 32-year-old Heather Heyer, the sight of that flag seemed like a touching gesture of solidarity.

Then we saw the Confederate battle flag on the other side of the truck, also snapping in the breeze, as much an appalling symbol of racism as it was when the last shots of the Civil War were fired and Robert E. Lee surrendered to Ulysses S. Grant at Appomattox Courthouse more than 100 miles away.

In 2017, it seems ridiculous to have to say this, but here we are:

The values of the flag of the United States of America, a beacon of freedom and hope to millions around the world, are not consonant — and will never be consonant — with the Confederacy, which existed for one purpose and one purpose only: To guarantee and perpetuate the enslavement of an entire race of people.

To fly the two alongside each other as if they are somehow equal, as if there is no difference between them, is an offense to the memory of those who died in the service of Old Glory and the values of pluralism and freedom it symbolizes.

To do so is an offense to the memory of Heather Heyer.

And it is an offense to the memories of Lt. H. Jay Cullen, 48, and Trooper-Pilot Berke M.M. Bates, the two Virginia State Police Troopers who perished in a fiery helicopter crash on Saturday as they were assisting in public safety at the so-called “Unite the Right” rally.

There will be some among you who say the flag of Dixie is an expression of Southern pride and heritage, that the driver had the constitutional right to display the flag — no matter how offensive it was in the wake of that tragedy in Charlottesville.

You’d be correct on the latter count: Bad speech, no matter how loutish or hateful, is protected by the First Amendment — right up until the point where it becomes a threat to someone else’s safety.

But as to the former, there is no universe, no cosmos, no alternate time-line where that flag is a mere token of regional pride, as if it’s as harmless as a glass of sweet tea and a plate of biscuits.

It’s not. It won’t ever be that. Because it’s right there in the black and white of the Confederate Constitution, Article IV, Section 3, which reads in part, “In all such territory the institution of negro slavery, as it now exists in the Confederate States, shall be recognized and protected be Congress and by the Territorial government; and the inhabitants of the several Confederate States and Territories shall have the right to take to such Territory any slaves lawfully held by them in any of the States or Territories of the Confederate States.”

That’s for you states-righters and lost-causers out there who continue to delude yourselves into thinking that the Southern states were merely rebelling against the economic hegemony of the North.

They weren’t. They were protecting slavery. Period.

Batting back that hate is what brought Heyer and so many other counter-protesters to Charlottesville last Saturday, to peacefully shout down those who want to sanitize that history and perpetuate the disgusting myth of white supremacy and the hateful philosophy it espouses.

Look, I have no insight into the heart of that truck driver, so I don’t know if he was a white nationalist. If he was expressing some kind of misguided regional pride, or if he thought he was being “politically incorrect” and defiantly sticking two fingers up to the protesters in Charlottesville.

If I had the chance to talk to him, I would have asked him why he thought it was acceptable to fly those two flags alongside each other. I would have challenged him on the values that the Stars and Bars represent and asked him if he thought they were somehow consonant with the values of this country.

That’s because it takes all of us speaking up, saying loudly and unhesitatingly that the symbols of the Confederacy, its statues and iconography belong in museums and history books, not in our town squares, and not flying on our front porches.

This one’s a no-brainer. We owe it to ourselves, to our children, to our neighbors, and to our country to immediately confront hate when we see it; to counter it with better speech, and to not stop fighting it until we banish it from our midst.

Yes, that’s a tall order. And we may never be totally victorious. But that’s the challenge that flag — Old Glory — poses to each of us.

JOHN L. MICEK, an award-winning political journalist, is the Opinion Editor and Political Columnist for PennLive/The Patriot-News in Harrisburg, Pa. Readers may follow him on Twitter @ByJohnLMicek and email him at jmicek@pennlive.com.