It’s been called “the most dangerous threat to American sovereignty”; “An anti-human document, which takes aim at Western culture, and the Judeo-Christian and Islamic religions,” that will bring “new Dark Ages of pain and misery yet unknown to mankind,” and “abolish golf courses, grazing pastures and paved roads,” in the name of creating a “one-world order.”

It’s been the subject of several forewarning books and DVDs; there are organizations dedicated to stopping it and politicians have been unseated for supporting it. Glenn Beck has spent a good portion of his career making people scared of it.

Not sure what it is? You’re not alone.

The Daily Beast got a sneak peek at a new report by the Southern Poverty Law Center, a nonprofit civil rights group, which deconstructs the mythology of Agenda 21 and the organizations, individuals, and even elected officials who’ve spent years promulgating the conspiracy theory surrounding it.

Before diving into the fiction that has inflated Agenda 21 to fear-mongering status, we must first understand the facts. What, exactly, is Agenda 21?

While the name might sound a bit ominous, Agenda 21 is a voluntary action plan that offers suggestions for sustainable ways local, state and national governments can combat poverty and pollution and conserve natural resources in the 21st century. (That’s where the '21’ comes from. Get it?) 178 governments—including the U.S. led by then-President George H.W. Bush—voted to adopt the program which is, again, not legally binding in any way, at the 1992 U.N. Conference on Environment and Development in Rio de Janeiro.

It wasn’t long after Agenda 21 was introduced that right-wing opposition began to swirl. The SPLC points to Tom DeWeese as one of the first pounce on the U.N. plan. In 1998 DeWeese founded the American Policy Center, a group based in Remington, Va., that focuses on “environmental policy and its effect on private property rights” and “the United Nations and its effect on American national sovereignty.” The SPLC report quotes DeWeese as describing Agenda 21 as a “blueprint to turn your community into a little soviet,” promoted by non-governmental organizations that pressure governments to enforce it. According to DeWeese, “It all means locking away land, resources, higher prices, sacrifice and shortages and is based on the age old socialist scheme of redistribution of wealth.”

DeWeese has continued to deride the dangers of Agenda 21 well into the 21st Century, making appearances on Fox News and fitting in nicely with the Tea Party movement. The American Policy Center was just the first of many anti-Agenda 21 organizations to spring up in the past 15 or so years and the SPLC points out the 11 most pervasive.

To those who don’t closely follow the carryings on of fringe conspiracists, Glenn Beck might be the most recognizable face of the modern Anti-21 movement. Particularly during his reign at Fox News, Beck used his cable TV soapbox to scare his loyal viewers. “Those pushing...government control on a global level have mastered the art of hiding it in plain sight and then just dismissing it as a joke,” the SPLC quotes Beck saying around 2011 while waving a copy of the 294-page Agenda 21 document on his show. “Once they put their fangs into our communities and suck all the blood out of it [sic], we will not be able to survive.”

Never one to miss an opportunity to cash on in people’s fears, Beck published a dystopian science fiction novel in 2012 called Agenda 21, about a version of America where mating partners are arranged, children are raised away from their parents in group homes, and the book’s heroine spends hours walking on a sort of treadmill that generates energy in an apartment in a planned community. In the book’s afterword, Beck warns, “[I]f the United Nations in partnership with radical environmental activists and naive local governments get their way, then the themes explored in this novel may start to look very familiar, very quickly.”

But while Glenn Beck can technically be dismissed as nothing more than a fringe figure, a conspiratorial talking head—no matter how large his audience may be—the elected officials who have taken a similarly strong stance against Agenda 21 cannot. In the report, the SPLC points out Newt Gingrich, who said he would “explicitly repudiate” the plan if elected president during his 2012 White House bid; Oklahoma Sen. Sally Kern and Arizona state Sen. Judy Burges who both introduced anti-Agenda 21 legislation that ultimately failed; and former Georgia Senate Majority Leader Chip Rogers, who “organized a four-hour, closed-door anti-Agenda briefing in October 2012” during which “attendees were told President Obama was using ‘mind control’ techniques to push land use planning, and that the U.N. planned to force Americans from suburbs into cities and also was implementing mandatory contraception to curb population growth.” U.S. Senator Ted Cruz (R-Texas) has claimed that Agenda 21 sought to abolish “golf courses, grazing pastures, and paved roads.”

And as recently as 2012, the SPLC writes, the Republican National Committee’s platform included the line, “We strongly reject the U.N. Agenda 21 as erosive of American sovereignty.”

Several anti-Semitic, neo-Nazi groups have also jumped on the anti-Agenda 21 bandwagon, seizing the opportunity to blame the controversial document on none other than the Jews.

“Anti-Semitism is basically a conspiracy theory,” the American Jewish Committee’s Ken Stern told the SPLC. He explains how neo-Nazis have linked Agenda 21 to the Protocols of the Elders of Zion, a falsified document that is alleged to reveal a secret Jewish plot to take over the world. “It’s Jews conspiring to harm non-Jews, and that conspiracy explains a lot of what goes wrong with the world,” Stern said.

To be sure, not all of Agenda 21’s opponents are on the far right of the political spectrum. The group Democrats Against U.N. Agenda 21 hosted a conference on the plan in California in 2011. Its founder, “self-described lesbian feminist Rosa Koire,” wrote the book Behind the Green Mask: U.N. Agenda 21, which claims the the plan will ultimately lead to the U.S.’s economic demise.

In fact, the anti-Semitic crowd’s interest in the Agenda 21 conspiracy theory sort of explains why it appeals to all of its followers, regardless of political leanings.

“Any time you get some sort of UN program that suggests any kind of change in the way people live, even if it seems outwardly benign and even voluntary, it’s going to be taken up by people with a conspiracist bent,” Michael Barkun, a Syracuse University political scientist and scholar of conspiracy theories, told the SPLC.

At this point in the explanation, it bears asking whether any of this matters. Is the federal government—or any state or local subsidiaries—even considering implementing any of the plan’s suggestions for sustainable development? The SPLC report states plainly: “For all the agitation, it’s not clear.” 98 percent of people who responded to a June 2012 poll by the American Planning Association said they didn’t know enough about Agenda 21 to support or oppose it. Six percent said they were against it, while nine percent stated that they were in favor.

The SPLC does note that some politicians, like Chattanooga, Tennessee Mayor Ron Littlefield, have denounced the anti-Agenda 21 conspiracists as modern-day Joseph McCarthys who will finally tire the public with their scare tactics. Still, they write, “an enormous number of politicians, commentators, activists, conspiracy theorists and others have swallowed the story of the anti-Agenda 21 zealots making any kind of rational discussion of the environment and related issues extremely difficult.”

“And that is the basic problem,” the report continues. “Dealing with the serious problems that confront our nation and our planet becomes incredibly difficult when the public discussion is poisoned with groundless conspiracy theories.”