Every four years, the pinnacle of American democracy is reached with the presidential election.

That’s when every eligible voter age 18 and older, from every town, city and hamlet across the nation, can listen to the candidates, examine their differing positions, go to the polls and cast his or her ballot for the next U.S. president.

It’s a significant time for our nation, and for the world, because of the pivotal role of our country — and our nation’s leader — in all manner of global affairs, from humanitarian assistance and trade deals, to war and peace and the deployment of troops.

Enter Donald J. Trump, the Republican candidate for president. He has turned this critical election into a nightmare with his continued ignorance, arrogance and insults.

The latest: The debacle with the Khan family of Charlottesville. 

Instead of simply respecting the feelings of the parents of decorated Army Capt. Humayun Khan, who sacrificed his life to save those of his fellow soldiers in a truck bombing during the Iraq War, Mr. Trump insulted them by pouncing on their Muslim religion. To add insult to injury, he arrogantly insisted that he, too, had sacrificed by building buildings and creating hundreds of jobs. Not stopping there, he had his campaign spokeswoman Katrina Pierson go on CNN Tuesday and ignorantly blame President Obama and his policies for the captain’s death.

Except Capt. Khan died in 2004, four years before President Obama first took office.

We remind Mr. Trump and his know-nothing operatives that Republican George W. Bush, who got us into the Iraq War with fake claims that Saddam Hussein had weapons of mass destruction, was president at the time.

Just days before this latest mess, Mr. Trump invited Russia to hack the emails of his Democratic opponent, Hillary Clinton.

“I will tell you this, Russia: If you’re listening, I hope you’re able to find the 30,000 emails that are missing,” Mr. Trump said at a July 27 news conference in Florida. “I think you will probably be rewarded mightily by our press.”

Mr. Trump’s campaign later attempted to back away from his statement, saying alternately that he was being sarcastic and that he wanted Russia to hand over the emails if they had them.

What?

Has Mr. Trump ever heard of Watergate and the resignation of former Republican President Richard Nixon over his administration’s attempted cover-up of its involvement in the break in at the Democratic National Committee’s headquarters at the Watergate building in D.C.?

What is Mr. Trump thinking?

It’s clear the Trump train is an express headed to Crazytown, and sadly, he’s trying to drag the country with him.

We are anxious and worried about the pending intelligence briefing with classified material typically given to presidential candidates. We believe it would be a dangerous mistake to trust Mr. Trump with such sensitive information.

This is too important for a person who repeatedly has demonstrated he has no filter and that he has a clear disdain for President Obama and his authority. What would happen should Mr. Trump disclose some of the classified material while on the campaign trail? He could cause serious harm to our nation and to the delicacy of diplomacy.

Despite this tradition dating to 1952, we urge President Obama to halt or scale back any briefing for Mr. Trump.

And we reiterate our call for Republicans to repudiate Mr. Trump’s views and, for the good of the nation, to replace him as the GOP standard bearer for president. If not, we have faith that people across the nation will show us by their vote in November what democracy looks like and dump Mr. Trump.

President Obama said it best in remarks we endorse:

“I think the Republican nominee is unfit to serve as president. I said so last week (at the DNC Convention), and he keeps on proving it,” President Obama said Monday. “He’s woefully unprepared to do this job.

“There has to come a point at which you say somebody who makes those kinds of statements doesn’t have the judgment, the temperament, the understanding to occupy the most powerful position in the world,” the president continued. “There has to come a point where you say, ‘Enough.’ ”