There were cheers when Donald Trump assured his Virginia audience last weekend that the wall will be built and, yes, that Mexico would pay for it. But the cheers lacked the roaring ecstasy his promise used to evoke at rallies. No one has the heart, by now, to pretend that such a wall will actually be built, but that’s all right with Mr. Trump’s dauntless fans, who can find plenty of other reasons for their faith in him. The NeverTrump forces, appalled at the prospect of a Trump presidency, are no less passionate.

The NeverHillary forces are another matter entirely—citizens well aware of the darker aspects of Donald Trump’s character but who have nonetheless concluded that they should give him their vote. They are aware of his casual disregard for truth, his self-obsession, his ignorance, his ingrained vindictiveness. Not even the first presidential debate, which saw him erupt into a snarling aside about Rosie O’Donnell, could loosen his hold on that visceral drive to inflict payback, in this case over a feud 10 years old.

The NeverHillary forces are aware, too, of his grandiosity—his announcement that he knows more about Islamic State than any of America’s generals will long be remembered—his impulse-driven character, his insatiable need for applause, the head-turning effect on him of an approving word from Vladimir Putin. The Russian leader’s compliment late last year was of the mildest kind—he referred to Mr. Trump as “talented” and “colorful”—but it was enough to make the candidate’s heart go pitter-patter with gratitude and engender instant expressions of his faith in Mr. Putin’s integrity and leadership. As Mr. Trump himself has explained, “if he says nice things about me, I’m going to say nice things about him.”

Such are the values that drive the Republican candidate’s judgment—a fact interesting to contemplate as one imagines a President Trump dealing with international conflict and rogue heads of state. Still Mr. Trump is now the choice of voters who have concluded that of the two flawed contenders running, he would be far preferable.

Yes, he may be rough around the edges, but he’s a fresh force, the argument goes, unlike the establishment war horse, Mrs. Clinton, with her history of scandal and rumors thereof, and her decades in politics. Mr. Trump is the dynamo who will blow up the old order. He’s authentic, a man with the courage of his convictions.

Mr. Trump has not, of course, shown himself notably reliable as regards the courage of his convictions. It’s by now impossible to count the number of times and ways in which he’s sidled away from his grand plans on immigration, that promise to deport everyone here illegally, not to mention his proposal to institute a total block on Muslim immigration “till we figure things out.” He’s proffered no less than three different views on abortion, one of which called for “at least some punishment” for the woman involved—quickly changed to wait, no, it should be the doctor.

Still, it was the view of Donald Trump as a fearless foe of liberal piety, that image of him as an outsider, untainted by experience in government—itself one of the more remarkable boasts of any presidential campaign in memory—that persuaded so many Americans he is the leader the country needs. As opposed, that is, to Mrs. Clinton—the educated former secretary of state, with lengthy experience in government.

Equally remarkable, even for a change election, that experience, those years of education in national security somehow rank high on the list of defects the anti-Hillary brigades find so objectionable. Here is a flaw apparently even more rankling than her email server history, the questions about Benghazi, or the Clinton Foundation: She offers nothing of Mr. Trump’s aura of free-swinging dynamism, not to mention a mind blissfully uncluttered by facts, knowledge of geopolitical realities, and the like.

Mrs. Clinton hasn’t failed to provide, on her own, cause for concern about her own proclivities and never more intolerably than in that debate Monday when she chose to ramble on, familiarly, about institutional racism, which invariably emerges in her responses on conflagration involving police action. Americans have a right to cringe at this reflexive, factually distorted, and inflammatory sermonizing. The accompanying, deep felt tribute to the police and their heroism, invariably added, can never offset the insidiousness of these messages.

Even so, such proclivities pale next to the occasion for cringing that would come with a Trump presidency. No one witnessing Mr. Trump’s primary race—his accumulation of Alt-Right cheerleaders, white supremacists and swastika devotees—could fail to notice the menacing tone and the bitterness that came with it.

Not for nothing did the Democrats bring off a triumph of a convention, alive with cheer, not to mention its two visitors whose story would lift countless American hearts. They were, of course, the Muslim couple Khizr and Ghazala Khan, whose son, Capt. Humayun Khan—brought here as a child—died in Iraq in 2004, saving his men from an explosive-rigged car.

His countrymen now go streaming to his grave at Arlington National Cemetery to leave notes and flowers. He reminded us of who we are—the nation that takes its newcomers and transforms them into Americans. After 9/11, Capt. Khan, American, could scarcely wait to serve his country. The national response to the Khans injected a sense of unity and affirmation, however brief, into an atmosphere of embittering divisiveness.

The end of the election is now in sight. Some among the anti-Hillary brigades have decided, in deference to their exquisite sensibilities, to stay at home on Election Day, rather than vote for Mrs. Clinton. But most Americans will soon make their choice. It will be either Mr. Trump or Mrs. Clinton—experienced, forward-looking, indomitably determined and eminently sane. Her election alone is what stands between the American nation and the reign of the most unstable, proudly uninformed, psychologically unfit president ever to enter the White House.

Ms. Rabinowitz is a member of the Journal’s editorial board.