Donald Trump, a man who may become our next president, put the First Amendment through its paces when he squared off with a Muslim-American couple who appeared on stage at the Democratic National Convention in Philadelphia last week.

Muslims have been a favorite Trump target during his campaign for the presidency. Last December, he called for "a total and complete shutdown" of Muslims entering the U.S., following the massacre in San Bernardino, Calif., that killed 14 people.

Immigrants have also been a favorite Trump target during his successful campaign for the Republican presidential nomination.

So it is hardly surprising that those positions made Trump a target during the coronation of Hillary Clinton at the Democratic convention.

Among those who appeared on stage were Khizr and Ghazala Khan, Muslim immigrants whose son – U.S. Army Capt. Humayun Kkhan – was killed by a roadside bomb in 2004.

"If it was up to Donald Trump, he never would have been in America," Khizr Khan said of his son as his wife stood by his side. "Donald Trump consistently smears the character of Muslims. He disrespects other minorities – women, judges, even his own party leadership. He vows to build walls and ban us from this country."

Shamelessly exploiting the parents of a dead soldier for Hillary Clinton’s political gain is hardly the Democratic National Committee’s finest hour, but Trump’s tone-deaf reaction to the Khans completely obscured that point, because it was bizarre even by his standards.

First, he suggested that Mr. Khan’s speech was written by the Hillary Clinton campaign and that Mrs. Kahn did not speak because her husband would not allow her to. As the Kahns explained later, she did not speak because – understandably – she wasn’t sure she could keep her composure while talking about her son.

Then, inexplicably, Trump compared his own "sacrifices" – whatever they might be – to those of the Khans and other parents who have lost children to war, a level of ignorance and narcissism that’s rare even for the world of politics.

Mr. Kahn went on television and said Trump is a man with "a black soul."

Trump should have let the matter drop there and taken his lumps. But that wouldn’t have been a very Trumpian thing to do.

Instead, the notoriously thin-skinned nominee took to Twitter on Monday and poured fuel on the fire: "Mr. Khan, who does not know me, viciously attacked me from the stage of the DNC and is now all over T.V. doing the same – Nice!"

Trump’s reaction to the Kahns has come in for all manner of scorn, making him, for the moment anyway, politically radioactive.

"You are not just attacking us, you are cheapening the sacrifice made by those we lost," wrote the Gold Star families, a support group for families who have lost relatives in battle.

Looking for a way out, Trump also tried misdirection, a favorite tactic of both candidates.

"Captain Khan, killed 12 years ago, was a hero, but this is about RADICAL ISLAMIC TERROR and the weakness of our ‘leaders’ to eradicate it!" Trump tweeted.

That was no help, either.

Perhaps because the American people have a funny way of deciding for themselves what things are "about."