There is something so unremittingly vile about Donald Trump.

A sheer lack of empathy and compassion, coupled with the distinguishing traits of a neighbourhood bully, has come to define the man who is now contending for the highest public office in the United States.

While Trump has disparaged politicians and even mocked a disabled journalist, he crossed all limits when he picked a fight with the grieving parents of Captain Humayun Khan, a Pakistani-American, who died in 2004 in Iraq while serving in the US Army.

Captain Khan’s parents Khizr and Ghazala Khan have shown tremendous courage and grace in standing up to America’s national bully.

In doing so, and in less than a week, the grieving parents of Pakistani origin have become the champions of the US constitution.

Also read: US Constitution sales soar after Trump challenge

Last Thursday, on the final day of the Democratic convention, with his wife Ghazala by his side, Khizr Khan delivered, what many political observers are calling, one of the most memorable moments from the Democratic Convention.

Khan challenged Trump about his knowledge of the US Constitution that proclaims liberty and equal protection of the laws.

He pulled a copy of the American Constitution from his pocket, and in a scene now repeatedly played on TV screens across the globe, he made an offer to Mr Trump, “I will gladly lend you my copy.”

However, the most memorable quote from Mr Khan came later, when he reminded Donald Trump:

You have sacrificed nothing and no one.

Donald Trump had the option to respect the loss of grieving parents whose beliefs he has maligned by suggesting banning Muslims from entering the US. Instead, he reacted very much like a classroom bully and questioned whether Ghazala Khan was not permitted to speak by her husband.

Yet, another unqualified attack on a mother who has made the ultimate sacrifice.

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It is no surprise that Ghazala Khan, like her brave son who saw death approaching, did not falter, chose to counter the bully. In an op-ed in the Washington Post, she explained to Donald Trump what most Americans heard in her grieved silence. She wrote:

Donald Trump has asked why I did not speak at the Democratic convention. He said he would like to hear from me. Here is my answer to Donald Trump: Because without saying a thing, all the world, all of America, felt my pain. I am a Gold Star mother [of a fallen soldier]. Whoever saw me felt me in their heart.

Again, showing nothing but apathy, Trump told the media that he too, has made sacrifices by creating businesses and thousands of jobs.

His definition of a sacrifice though leaves much to be desired. Mrs Khan rightly mentioned that perhaps Mr Trump “doesn't know what the word sacrifice means”.

The best among us

It was not just Mrs Khan who questioned Trump’s twisted definition of sacrifice. Speaking at a rally, one of America’s respected financiers Warren Buffett also called Trump out by pointing out that their families had amassed billions in the US, but have not sacrificed the way military families had.

“How in the world can you stand up to a couple of parents who lost a son and talk about sacrificing because you were building a bunch of buildings?” rightly questioned Mr Buffett.

Senator John McCain, a war veteran and a former Republican nominee for the Presidential elections, too, found Donald Trump’s offensive attacks on grieving Muslim parents too much to ignore. He protested in the strongest terms possible.

“While our Party has bestowed upon him the nomination, it is not accompanied by unfettered license to defame those who are the best among us,” he said in a statement.

The Senator, obviously troubled by the xenophobic diatribe of the Trump campaign that attacked all minorities, continued and thanked the Khan family for making America their home:

“I'd like to say to Mr and Mrs Khan: thank you for immigrating to America. We’re a better country because of you. And you are certainly right; your son was the best of America, and the memory of his sacrifice will make us a better nation — and he will never be forgotten.”

See: Fight with Khan family tests Trump’s ‘say anything’ strategy

While the Trump campaign was issuing directives to staff to pivot away from the Khan controversy, Trump was busy digging himself deeper into a pit of hate and prejudice.

Speaking to the media yesterday, he falsely accused Mr Khan of belonging to the Muslim Brotherhood (an Egyptian Group with almost no non-Arab following), trying to bring in militants to the United States.

That these statements are utterly false and that Mr Trump has no evidence to offer in support of his accusations speaks volumes about his mental health. His erratic behaviour and malicious attacks forced President Obama to question his sanity by declaring that Mr Trump is “unfit to serve as president.”

Earlier, the former Mayor of New York and a billionaire businessman, Michael Bloomberg, asked Americans to “elect a sane, competent person,” alluding to Mr Trump’s questionable sanity.

Others have raised similar concerns about Mr Trump possibly suffering from a multiple personality disorder, lack of sound mind, or being “just plain crazy.”

Warren Buffett, who is a billionaire like Mr Trump, recently reminded Americans of Senator Joseph McCarthy whose witch-hunt in the 50s targeted those suspected of being communist sympathisers. Joseph Welch, a lawyer, appearing before Senator McCarthy, asked the very question that started the end of McCarthyism in the US. Mr Welch pointedly asked Senator McCarthy,

“At long last, have you left no sense of decency?”

Years later, America is witnessing another manifestation of McCarthyism where all minorities, religious or racial are being made suspects by the Trump campaign.

Time will tell whether Trump is of sound mind or not, but the Khizr Khan episode has proved that he is certainly not of sound judgement. And so I stand with Mr Buffett in asking Donald Trump:

“Have you no sense of decency, sir?”