When all’s said and done, it will be the Khan moment that forever altered the 2016 presidential election.

Donald Trump will never recover from it.

It won’t be his vulgar sniping at Megyn Kelly of Fox News, the Mexican rapist remark or his race-based disparagement of a federal judge that will have killed his candidacy.

It won’t even be Trump’s belittling of Arizona Sen. John McCain for being shot down and captured during the Vietnam War, his suggestion that Second Amendment advocates might want to knock off his Democratic opponent or that a sitting U.S. president is the founder of a global jihadist organization. All those things, somehow, could have been forgiven by enough voters to make the New York businessman competitive in November.

But not his dust-up with the parents of a dead U.S. Army officer. There Trump mortally wounded himself.

It’s perfect in a way — Shakespeare perfect.

When Khizr Khan, the father of the late Army Capt. Humayun Khan, held a copy of the Constitution above his head at the Democratic National Convention in Philadelphia, it changed everything. And not just in the race. It created a new and needed national iconic moment that spoke to American exceptionalism both here and abroad.

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It said to Muslims and others around the world, that every American is a full citizen, made equal by the promises in this document. And it told nervous post 9/11 Americans of other backgrounds that Muslim Americans are as red-white-and-blue as you are. We are all in. My wife and I gave our son for the ideals I’m holding in my hand.

But then it got better.

After Trump disparaged Ghazala Khan, Capt. Khan’s mother, by suggesting she was a subservient wife disallowed to speak at the convention by her husband, an extraordinary thing happened. Americans of every stripe, color and political leaning rallied to the Khans’ defense. Military people, especially, called out Trump for his cruel stupidity. They said, in effect, that when you mess with the Khan family, you mess with us. Capt. Khan is our brother. He’s one of us.

It was everything that needed to be said about America, and the world couldn’t help but notice.

Not everyone was gracious. Unfortunates such as longtime Trump supporter Roger Stone tried spreading rumors about the deceased Army captain — rumors so vile that they will not be repeated here — but the national balance of sentiment was so clearly in favor of the Khan family that scores of leading Republicans renounced Trump.

Young people are protesting at Trump rallies by holding up copies of the Constitution. Constitutional conservatives couldn’t engender such support for the guiding U.S. document in 100 years. Only a grieving American father and Trump’s mouth could do that.

A college classmate and ardent Trump supporter complained on my Facebook page last week that flowers were being left on Capt. Khan’s grave at Arlington National Cemetery in Virginia. What about the others there?

That’s a fair point. Every American who gives his or her life for this country deserves to be remembered and honored, always. But the flowers on Khan’s grave come with special importance. The 27-year-old University of Virginia graduate didn’t just give his life for this country — the symbolism of his sacrifice may very well have saved it.

American Army Capt. Humayun Saqib Muazzam Khan, RIP.

William F. B. O’Reilly is a consultant for Republicans.