Debating Stephen Douglas over slavery, Abraham Lincoln said a house divided cannot stand. In 2018, we also are a house divided and must ask whether the terrible biblical saying Lincoln quoted applies to us. Can we endure as a united country?

We thought our politics couldn’t get any crazier, but the political divide and the breakdown in trust became even deeper after the Brett Kavanaugh hearings. When Anita Hill accused Clarence Thomas of sexual harassment, we were permitted to disagree about who was telling the truth. No longer. This time you’re “complicit with evil” if you don’t believe his accusers and oppose Kavanaugh, said Sen. Cory Booker (D-NJ).

Moral outrage has become the basic currency of political debate, with Hillary Clinton telling her supporters, “You cannot be civil,” and former Attorney General Eric Holder advising, “When they go low, we kick them.” So have we, as a story in The Washington Post says, hit rock bottom with no clear path up?

After Kavanaugh was confirmed, liberal columnist E.J. Dionne wrote that the Supreme Court’s legitimacy is in tatters. Kavanaugh was nominated by the president, as the Constitution requires, but many liberals think Trump an illegitimate president because more people voted for Clinton. As for the Senate, which confirmed Kavanaugh, it’s undemocratic because little North Dakota has the same number of senators as California.

This amounts to a claim that all three branches of government are illegitimate. To those making such claims, it’s the Constitution itself that is illegitimate.

Before the 2016 election, Trump said he might not accept its results. Clinton said this was horrifying and cast doubt on the legitimacy of our institutions. But after Trump won, it was Clinton who joined the “Resistance,” and what has followed is nothing more than the working out of that movement’s grim logic.

As legislators, you’d think Democratic congressmen would understand what it means to question a government’s legitimacy. Apparently not. Sen. Ed Markey (D-Mass.) has called Trump an illegitimate president, but if that’s the case the military would be excused from obeying his orders as commander-in-chief.

Perhaps that’s just what Markey thought. His colleague in the House, Steve Cohen (D-Tenn.), tweeted that the military should mount a coup, as they do from time to time in South America.

When our political leaders tell us the Constitution is illegitimate, that we’re a hair’s breath from fascism, that’s how a civil war begins. Is it impossible to imagine? When polled, 31 percent of likely voters think that there will be a second Civil War within the next five years. That’s made secession look attractive, and nearly two-fifths of Americans tell pollsters they want to secede.

We’ve not seen anything like this since the 1850s. As for what happens next, who knows?

Were the GOP to hold its majorities in Congress next month, the Democrats might possibly come to terms with their defeat and abandon their infantile protests. I don’t expect that to happen, mind you. The party is so invested in its hatreds that it’ll not give them up.

If that’s where we are now, picture what it might be like in a future America, where Trump has won re-election and both houses of Congress remain in Republican hands.

Suppose further that Ruth Bader Ginsburg and Stephen Breyer have left the Supreme Court, and Trump fills both seats with conservatives. From prominent Democrats, there are daily calls for resistance in the streets, and our restaurants and theaters have turned into no-go zones for people of the wrong political party.

Were that to happen, Lincoln’s “house divided” would have new meaning, and we’d begin to wonder whether we all belong in the same country. “Some of those folks — they are irredeemable, but thankfully they are not America,” said Clinton, about the millions of “deplorables.” Yet if they’re not Americans, they might reasonably ask themselves to what country they belong or should belong.

Maybe we should stare the possibility of a breakup in its face, if we’re ever to regain our old civility and affection for fellow Americans. Before criminalizing honest policy differences, before the online shaming, the Twitter mobs and the no-platforming, before doxing ideological enemies, let’s recall that those enemies just might have exit options.

F.H. Buckley wrote “The Republican Workers Party: How the Trump Victory Drove Everyone Crazy, and Why It Was Just What We Needed.”