Two conspiracy theorists were arrested Monday after allegedly threatening a pastor at the Texas church where 26 people were killed in a 2017 mass shooting, which the couple claim was staged by the U.S. government.

First Baptist Church of Sutherland Springs pastor Frank Pomeroy found Robert Ussery and Jodi Mann writing, “The truth shall set you free” on a church poster hung up for well-wishers to sign. Pomeroy intervened, prompting a tirade from Ussery, who was filming the interaction with a camera on his chest.

Ussery “continually yelled and screamed and hollered and told me he was going to hang me from a tree and pee on me while I’m hanging,” Pomeroy told the San Antonio Express-News. “He kept trying to bait us to do something dumb.”

In the rant, Ussery denied the victims’ existence and demanded to see the birth certificate of Pomeroy’s 14-year-old daughter, who was killed in the attack. “He said, ‘Show me anything to say she was here,’ ” Pomeroy said.

A nearby church member called police, who arrested the pair and booked them into the county jail, the Express-News reported.

Ussery, 54, and Man, 56, believe that mass shootings, including the Nov. 5 massacre at the church, are hoaxes organized by the U.S. Department of Homeland Security. On Ussery’s website Side Thorn, he also claims the shootings at Marjory Stoneman Douglas High School in Parkland, Florida, and Sandy Hook Elementary School in Newtown, Connecticut, never happened.

Side Thorn’s accompanying Twitter account, which has nearly 1,400 followers, links to homemade videos on the site. One video in the aftermath of Sutherland Springs shows “exclusive footage” of allegedly staged and rehearsed activities that Ussery says prove that crisis actors filmed the shooting at an earlier date.

Pesky conspiracy theories like the ones Ussery and Mann promote resurface often after mass tragedies. In the wake of the Feb. 14 school shooting in Parkland, the top trending video on YouTube pushed the lie that 17-year-old survivor David Hogg was a crisis actor hired by left-wing activists. It accumulated 200,000 views before YouTube removed it.

In the age of viral media, conspiracy theories can become especially dangerous. Each time a reader encounters a false story on Facebook, YouTube, or Twitter, that story becomes more and more familiar, increasing the chances someone will consider it to be true. The fact that President Donald Trump tolerates, and even indulges in, many conspiracy theories is a bad sign for the prospects of a serious gun policy debate.