By Karen Tumulty

The Washington Post Opinion

Give President Donald Trump's most loathsome supporters this much: They don't hide who they are.

A year ago, it was the white supremacists marching in Charlottesville. Now, just look for people wearing shirts and carrying signs with the letter "Q" at Trump rallies. They were all over the place in the crowd that showed up for the president's speech Tuesday night at the Florida State Fairgrounds Expo Hall in Tampa.

Most sane people had probably never heard of the QAnon until recently, though its theories would occasionally surface when spread by people such as actress Roseanne Barr and former Boston Red Sox pitcher Curt Schilling. Its information supposedly comes from "Q," an anonymous poster on several image boards who claims to be a government agent with top-secret clearance.

It is what a Post headline accurately described as a "deranged conspiracy cult," one that has crawled out of the malodorous crevices of the Internet where decent people don't go. That it would announce its presence in public is both horrifying and perfectly predictable, given how racist lies that Barack Obama was born in Africa helped launch Trump on his path to the White House. The movement, if you care to dignify it by calling it one, is Birtherism 2.0.

QAnon followers have a delusional fixation on pedophilia, an outgrowth of the #Pizzagate lie that went viral shortly before the 2016 election. That one, you might recall, ended up with a gunman opening fire in a D.C. pizza restaurant as he searched for children he thought were being trafficked from the establishment's nonexistent basement by Hillary Clinton and her campaign chairman John Podesta. But those sick theories are only one book in QAnon's Canon of Crazy, as my colleague Isaac Stanley-Becker reports:

"But viewing their message boards, it's clear that QAnon crosses a new frontier. In the black hole of conspiracy in which 'Q' has plunged its followers, Trump only feigned collusion to create a pretense for the hiring of special counsel Robert Mueller, who is actually working as a 'white hat,' or hero, to expose the Democrats. Barack Obama, Hillary Clinton and George Soros are planning a coup - and traffic children in their spare time. J.P. Morgan, the American financier, sunk the Titanic.

"In the world in which QAnon believers live, Trump's detractors, such as Republican Sen. John McCain of Arizona and Hillary Clinton aide Huma Abedin, wear ankle monitors that track their whereabouts. Press reports are dismissed as 'Operation Mockingbird,' the name given to the alleged midcentury infiltration of the American media by the CIA. The Illuminati looms large in QAnon, as do the Rothschilds, a wealthy Jewish family vilified by the conspiracy theorists as the leaders of a satanic cult. Among the world leaders wise to satanic influences, the theory holds, is Russian President Vladimir Putin."

Only slightly less offensive than the QAnon presence - and really, the bar is getting pretty low here - was the contingent of Trump supporters at the Tampa rally captured on video by one of their favorite targets, CNN's Jim Acosta.

"Just a sample of the sad scene we faced at the Trump rally in Tampa," Costa wrote on Twitter, describing the video. "I'm very worried that the hostility whipped up by Trump and some in conservative media will result in somebody getting hurt. We should not treat our fellow Americans this way. The press is not the enemy."

Many of these middle-finger-waving, F-bomb-hurling people probably think of themselves as pillars of their community, guardians of fundamental values. This kind of behavior, in their view, is just an expression of their patriotism.

Surely, people such as these do not represent the majority of those who voted for Trump, or who continue to support him. And we have had other periods in our history when conspiracy theories - that the moon landing was a hoax, for example, or that John F. Kennedy's assassination was an inside job - have gained semi-wide circulation. But with the internet, sick minds can find and reinforce one other in ways they never have before.

Benjamin Franklin once said: "Whatever is begun in anger, ends in shame." But what happens when human beings lose their ability to feel shame? There is a real possibility that the forces Trump has unleashed may not go away when he does. And that may be the saddest, scariest thing of all.

-- Karen Tumulty is a Washington Post columnist covering national politics. She joined The Post in 2010 from Time magazine and has also worked at the Los Angeles Times. @ktumulty