It was the latest in a series of increasingly nasty comments about McCain: Sen. Orrin Hatch, a Utah Republican, called it "ridiculous" that McCain wasn't planning to invite President Donald Trump to his funeral while a retired general on Fox News on Thursday referred to a debunked conspiracy theory that McCain had informed on his comrades while a prisoner of war during Vietnam.

There's no disputing the fact that McCain has terminal brain cancer and that he is very unlikely to be around at this time next year. It's also indisputable that McCain is a genuine American hero -- who fought and suffered for his country in the theater of war and had decided the better part of the last four decades of his life to public service as a House member, a senator and a two-time presidential candidate.

That even some part of his final days -- or weeks or months -- is consumed by this sort of garbage is maddening. And depressing. And made even more so by the fact that this is, in fact, the new normal.

How did we get here? Where anyone who disagrees with us on anything is evil, other and an object for ridicule? Where the phrase "reasonable people can disagree" has lost all meaning? Where someone can feel comfortable making a death joke about a man battling brain cancer?

Lots of people would like to lay the blame -- all of it -- at the feet of Trump. The reality is more complex. Our own self-sorting tendencies -- we rarely live around anyone anymore who doesn't see the world generally as we do -- played a role. The expansion of ideological media where you can only watch, read and listen to people who validate you and your views played a role. The rise of outside political groups who made a business out of purifying the two parties of any so-called moderates played a role. The partisan redistricting processes around the country, which jammed us into congressional seats prioritized by political party played a role.

That said, there is no question that Trump -- the campaign he ran in 2016 and the way he has acted in the White House since winning -- has been the prime catalyst for this degradation in our ability to simply treat people with whom we disagree with respect.

There was already lots of gasoline on the ground. Trump lit the match and dropped it.

Trump's campaign was based on a simple idea: Politicians are too political. They're afraid of their own shadows. They won't say it like it is because they live in fear of the political correctness police coming to knock on their door.

He cast himself as the antidote to all of that -- someone who would say what everyone was thinking. He was a status quo shaker, the worst nightmare for the staid and ineffective political establishment.

That idea, in and of itself, is powerful.

The problem was -- and is -- that Trump conflated insults and bullying with shaking things up. So, questioning McCain's war credentials -- "He's not a war hero. He was a war hero because he was captured. I like people who weren't captured." -- as Trump did in July 2015, at the start of his presidential campaign, was somehow treated by Trump and those who supported him as speaking truth to power.

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Ditto his attacks on Carly Fiorina's looks. His attempts to raise the heritage of Judge Gonzalo Curiel. His suggestion that Khizr Khan, the father of a solider fighting in Iraq, had been put up to his speech at the Democratic National Convention by partisans out to get him. His suggestion, as President, that "both sides" were to blame for the white nationalist violence in Charlottesville, Virginia. His repeated bullying of his attorney general, Jeff Sessions, and his comments about the alleged plastic surgery of "Morning Joe" anchor Mika Brzezinski

On and on the list goes. And it all adds up to one thing: Trump weaponized nastiness and bullying. He turned it into a political art form. He gave cover for all of those people with uninformed views -- on race, ethnicity and everything else -- to emerge from the shadows and speak out.

And, if you didn't laugh or "get the joke" -- even though Trump was often not joking in these circumstances -- you were part of the problem. Just another defender of a status quo that rewarded elites and left out the little guy. Just another person who didn't get it.

The issue with all of this is that it bastardized a very legitimate issue -- the growing income (and everything else) gap between the rich and the poor -- for Trump's own political purposes. He drove the divide for political reasons and, in his language, made it totally OK to say whatever you wanted about people you disagreed with because they had been out to get you for years. This was just payback. And man did they deserve it.

Nuance went out the window. Speaking hard truths that the country needed to hear -- as McCain has done throughout his career -- became indistinguishable from calling Sen. Ted Cruz's wife ugly or suggesting that we need to ban Muslims from entering the country. Political incorrectness became a crutch to justify racist and xenophobic views.

And in the middle of it all was Trump. When he wasn't engaging in these behaviors, he was refusing to condemn them -- an example of his abdication of the idea of the President as moral leader. Who am I to say who is right and who is wrong in the Charlottesville violence, Trump asked. Who am I to judge who is telling the truth -- Roy Moore or the multiple women who said he had pursued relationships with them when they were teenagers?

That view has trickled down. When CNN's Chris Cuomo asked State Department spokeswoman Heather Nauert on Friday to comment on the "joke" about McCain's death, Nauert responded: "I'm not familiar with what you're familiar with." Really? Nauert hadn't heard about the story? I find that very, very hard to believe.

That collective shrug from the President of the United States and his allies coupled with the extant factors of our internal divisions and the sort of campaign he ran in 2016 created the toxic stew from which comments like the one Thursday by Sadler grow.

No one is standing up and saying "We can't treat people like this." And sadly, that vacuum in moral leadership means that the better angels of our nature are being drowned out by our demons.