Charlie Kirk is being eulogized and his family prayed for by all of America’s living presidents. His murder is a reminder of our mortality, the kind of atrocity that prompts people to seek comfort in religion. But for much of the electorate, their creed is politics, which prevents us from echoing our presidents and uniting to end this season of violence.

Twenty-four years ago today, the 9/11 attacks reminded us that our enemies seek to slay all Americans, not just Republicans or Democrats, white or black, gay or straight. They hate us because we are the watchmen in President Reagan’s “shining city on a hill” and our existence threatens those who’d deny liberty to others.

After the second assassination attempt on President Trump last September, this columnist wrote in The New York Sun, warning, “The Assassination Fire Is Burning, Threatening To Spread Across America If Not Stopped.” Everyone has a stake in quenching those flames.

Assassinations, I wrote, have come in “seasons” throughout our history, emerging at “times when citizens lost confidence in the ability of democratic institutions to resolve disputes.” Those periods ended only when Americans saw, as President Lincoln told North and South in his first inaugural, “We are not enemies, but friends.”

The Framers of the Constitution, aware that Americans would disagree, sought to harness discord rather than squelch it. They diffused power across the three branches of the federal government and between it and the states. The First Amendment prohibited banning speech so people could talk out disputes without resorting to violence.

That shared legacy will be easy to forget once the motive and politics of Kirk’s killer is known. When those details emerge, they’ll be used to craft competing narratives. Kirk will become an afterthought, allowing partisans to slide back into their comfortable red or blue bunkers.

Yet hunkering down in an assigned trench, surrounded by like-minded allies, wasn’t Kirk’s style of citizenship. He crawled out into No-Man’s Land, meeting his opponents to negotiate one-on-one versions of World War I’s Christmas truces.

At the time of Kirk’s shooting, I was reflecting on the absence of social media on 9/11 and my “History Author Show” interview with a New York Republican, Governor George Pataki. America’s national conversation then wasn’t flooded with bots and anonymous handles. Conversations were more sincere than preening for clicks.

Mr. Pataki, in his book, “Beyond the Great Divide,” recounted uplifting stories from that dark day. “The big thing now,” he told me, is to write best-selling books about “how this politician is awful, or Democrats are criminals, or Republicans are racists.”

Such books give “red meat,” Mr. Pataki said, to “rabid followers.” Those who “offer solutions and create a more nuanced approach” are vilified. Examples include outrage over a liberal actress, Ellen DeGeneres, appearing with President George W. Bush at a Dallas Cowboys game, and the Republican governor of New Jersey, Chris Christie, embracing President Obama after Superstorm Sandy.

Kirk was unafraid of such backlashes. He went to college campuses seeking out those who disagreed rather than lobbing insults without ever looking into their eyes. Young people who might have never talked to a conservative before were reminded that free speech means tolerating uncomfortable points of view.

Partisanship emerged across social media and in the press as Kirk’s fate unfolded. TMZ called “tone deaf” laughter in their newsroom at confirmation of his death. MSNBC fired an on-air commentator, Matthew Dowd, for saying, “hateful thoughts lead to hateful words which then lead to hateful actions.”

There will be more who use the killing of Kirk to craft political barbs in the coming days. The result will be to stack more sandbags along the trenches, forgetting that the man who lost his life preferred civil conversations that employed the tools enshrined in the Constitution.  

Where other commentators grow wealthy preaching to the choir, Kirk sought to persuade those who might never support his sponsors or buy his books. “When people stop talking,” he said in one conversation, “that’s when you get violence … because you start to think the other side is so evil and they lose their humanity.”