Donald Trump. Reuters/Carlo Allegri Have you no sense of decency, sir?

Those are the words that I keep reflecting on when I think of Donald Trump and his supporters as they launch attacks on a Gold Star family who spoke out at the Democratic National Convention.

In an emotional speech, Khizr Khan — father of Capt. Humayun Khan, a Bronze Star hero killed in the Iraq War — said that if it were up to Trump, then his son probably would not have been able to be in the US, let alone its military.

And he asked whether Trump had read the US Constitution, while opining that he had never sacrificed anything in his life.

It was all legitimate criticism and questioning: Trump had called for a "total and complete shutdown of Muslims entering the United States" last year, despite various legal scholars calling such a ban a clear violation of the Constitution.

And when later asked of what personal sacrifices he had made for his country by ABC's George Stephanopoulos, Trump couldn't recall anything other than his business success and that he had "created thousands and thousands of jobs."

Sacrifice is defined as the "act of giving up something that you want to keep especially in order to get or do something else or to help someone." So, I would ask, how is Trump working hard to build a business a sacrifice?

And I would ask again: Have you no sense of decency, sir?

Khizr Khan challenges Republican presidential nominee Donald Trump to read his copy of the US Constitution at the Democratic National Convention in Philadelphia, Pennsylvania. Thomson Reuters

A few know what the ultimate sacrifice looks like firsthand. They are the Gold Star mothers and fathers, and they count the parents of Capt. Khan within their ranks. All have once heard a knock at their door, a soldier and chaplain behind it, charged with delivering the news that no parent ever wants to hear.

Trump also implied that Ghazala Khan's Muslim faith was the reason why her husband spoke at the convention and she did not. But what stopped her from speaking was her incredible grief, as she explained in The Washington Post.

"Walking onto the convention stage, with a huge picture of my son behind me, I could hardly control myself," she wrote. "What mother could? Donald Trump has children whom he loves. Does he really need to wonder why I did not speak?"

Perhaps this shouldn't be so shocking, considering that Trump had no problem attacking a man held captive and tortured for more than five years in a North Vietnamese prison camp.

But it will never be right. And it's more than politics — it's about basic human decency.

Trump said that "Mr. Khan [had] no right to stand in front of millions of people and claim" that he had never read the Constitution — a coincidental statement, given that Khan was demonstrating his First Amendment right to freedom of speech.

Now contrast Trump's view with President George W. Bush, who was asked about Cindy Sheehan, the mother of Army Spc. Casey Sheehan, who was killed the same year in Iraq as Capt. Khan. As Sheehan held an anti-war vigil outside Bush's ranch in Crawford, Texas, in 2005, he told reporters:

"I sympathize with Mrs. Sheehan. She feels strongly about her position, and she has every right in the world to say what she believes. This is America. She has the right to her position. And I thought long and hard about her position — I've heard her position from others, which is 'get out of Iraq now.' And it would be a mistake for the security of this country and the ability to lay the foundations for peace in the long run if we were to do so."

The tombstone of US Army Capt. Humayun S. M. Khan is seen in Section 60 at Arlington National Cemetery in Arlington, Va., Monday, Aug. 1, 2016. Fellow Republicans are joining the rising chorus of criticism of Donald Trump for his disparagement of the bereaved parents of U.S. Army Capt. Humayun Khan, a Muslim who was awarded a Bronze Star after he was killed in 2004 in Iraq. Carolyn Kaster/AP

While visiting a dying soldier at Walter Reed that year, Bush was even berated by a devastated mother, as his press secretary, Dana Perino, recounted. He tried to offer comfort, but eventually, he just stood there and took it.

Bush knew that, at the end of the day, it was ultimately his fault that that mother's son was in a hospital bed. Though he believed that the Iraq War was just, his decision to invade in 2003 was one that was his alone.

"I don't blame her a bit," he told Perino.

He had the dignity to let a grieving family vent. Why can't Trump?

"You are not just attacking us, you are cheapening the sacrifice made by those we lost," more than a dozen Gold Star families wrote in a letter calling on Trump to apologize.

So, Mr. Trump, I'll ask again: Have you no sense of decency, sir?

And to the ranks of the Republican Party — beyond a handful who have spoken out yet refused to withdraw their support — that continue to remain deafeningly silent as a Gold Star family is attacked by its candidate for US president: People will remember that you would not condemn a man who may some day walk into a hospital room of a grieving family angered that he sent their son or daughter to war.

So I would ask all of them: Have you no sense of decency?

Paul Szoldra is a correspondent for Tech Insider and a US Marine infantry veteran of the war in Afghanistan.