Foreign governments like Russia, China, Iran and others have also pushed extremist content on social media as part of their efforts to destabilize western democracy. Russia has amplified numerous anti-U.S. conspiracy theories, including ones claiming the U.S. runs secret germ warfare labs, created HIV as a bioweapon, as well as conspiracy theories accusing Ukraine of being a Nazi state, or of attempting to commit genocide against Ukrainians.  

China, meanwhile, has helped to spread claims that the U.S. created COVID-19 as a bioweapon and that the wildfires in Maui were deliberately set. 

Tom Fishman, the CEO at the non-profit StartsWithUs, said he agrees that groups looking to sew disunity and distrust in the U.S. will continue to harness conspiracy theories, but that Americans can take steps to defend the social fabric. He said people need to turn off the computer and meet the people they disagree with, and they'll find their opponent isn't the bogeyman they've been led to believe. Americans must remember what ties them together, he said. 

“We can look at the window and see foreshadowing of what could happen if we don’t: threats to a functioning democracy. Threats of violence against elected leaders,” he said. “We have a civic duty to get this right.” 

Polls and research surveys on conspiracy theories show about half of Americans believe in at least one conspiracy theory, and those views seldom lead to violence or extremism. But for some, these beliefs can lead to social isolation and radicalization, interfering with their relationships, career and finances. And for an even smaller subset, they can lead to violence. 

The credible data that exists on crimes motivated by conspiracy theory shows a disturbing increase. In 2019, researchers at the University of Maryland’s National Consortium for the Study of Terrorism and Responses to Terrorism identified six violent attacks in which the perpetrator said their actions were prompted by a conspiracy theory; in 2020, the year of the most recent survey, there were 116. 

“There’s no question that extremist groups are using conspiracy theories to spread their message and recruit new members,” said Cynthia Miller-Idriss, director of the Polarization and Extremism Research and Innovation Lab at American University, which studies far-right extremism. “The internet is the means for doing that. And while belief in conspiracy theories doesn’t automatically mean someone is going to become an extremist, we can say that a lot of extremists share those beliefs and are trying to put them into action.” 

In 2016, fringe websites were flooded with claims that Hillary Clinton and other top Democrats were hiding child sex trafficking victims in Washington, D.C. pizzerias. The claim spread quickly on platforms like Reddit, YouTube, 4chan and Twitter, where it was amplified by white supremacists and far-right Trump supporters. A North Carolina man armed with a rifle forced his way into one pizzeria and fired his weapon. No children were found, but the debunked claim still circulates online. 

To believers, the facts didn’t matter. 

“You can create the universe you want,” said Danielle Citron, a University of Virginia professor who studies online harassment and extremism. “If the truth doesn’t matter, and there is no accountability for these false beliefs, then people will start to act on them.” 

Sell, the conspiracy theorist from Pennsylvania, said she began to lose trust in the government and the media shortly after the 2012 Sandy Hook school shooting in Newtown, Conn., which left 20 students and six teachers dead. Sell thought the shooter looked too small and weak to carry out such a bloody act. And the gut-wrenching interviews with stricken loved ones seemed too perfect, almost practiced. 

“It seemed scripted,” she said. “The pieces did not fit.” 

That lie — that the victims of the rampage were actors hired as part of a plot to push gun control laws — was notably spread by conspiracy theorist Alex Jones. The families of Sandy Hook victims sued, and the Infowars host was later ordered to pay nearly $1 billion in damages. 

Sell said she believes the level of distrust is now so high that a civil war or some other kind of uprising could happen — but that it would be the government that starts it. 

“If enough people start asking questions, the government is going to do what it can to shut it down,” Sell predicts. “It would probably get to a point of martial law.” 

Fear of persecution by the government is a common theme in many conspiracy theories with ties to extremism.  

In 2018, a committed conspiracy theorist from Florida mailed pipe bombs to CNN, Clinton and several other top Democrats; the man’s social media feed was littered with posts about child sacrifice and chemtrails — the debunked claim that airplane vapor clouds contain chemicals or biological agents being used to control the population. 

In another act of violence tied to QAnon, a California man was charged with using a speargun to kill his two children in 2021; he told an FBI agent that he had been enlightened by QAnon conspiracy theories and had become convinced that his wife “possessed serpent DNA and had passed it on to his children.” 

The coronavirus pandemic created ideal conditions for new conspiracy theories, as the virus spread fear and uncertainty around the globe. Vaccine clinics were attacked, doctors and nurses threatened, and 5G communication towers were vandalized and burned as a wild theory spread claiming they were being used to activate microchips hidden in the vaccine. Fears about vaccines led one Wisconsin pharmacist to destroy a batch of the highly-sought after immunizations, while bogus claims about supposed COVID-19 treatments and cures led to hospitalizations and death.