QAnon is getting its first congresswoman.

Marjorie Taylor Greene won a runoff in a Republican primary Tuesday, all but assuring her victory in November in a heavily GOP district.

She is thus set to become the highest officeholder in the land who takes seriously the lunatic theories of QAnon, the anonymous internet poster who says, among other ludicrous and poisonous things, that there’s a global network of pedophiles about to be exposed and undone by President Donald Trump.

Greene’s ascension is the latest indication of the creeping influence of Q, who has fashioned a kind of free-floating John Birch Society for the digital age. The author’s adherents or fellow travelers are adept at spreading memes on social media, hold signs or wear paraphernalia touting Q at Trump rallies, and now are notching some victories in GOP primaries.

Jo Rae Perkins, a no-hoper who won the Republican Senate primary in Oregon, has associated herself with Q and expressed disappointment when her sellout campaign team tried to hide her enthusiasm for the conspiracy theory. Lauren Boebert, the upset winner of a primary for a Republican House seat in Colorado, said of Q in a radio interview, “If this is real, then it could be really great for our country.”

The rise of Q shouldn’t be exaggerated. Surely, most Republicans aren’t even aware of this dreck, and the Q caucus in the next Congress might number around one or two. Almost every political movement has a fringe that marinates in paranoia and is prepared to believe – or invent – the worst about the other side.

Yet, the spread of QAnon shows that the Trump-era GOP has weakened antibodies against kookery. Trump himself sets the tone. He’s an indiscriminate tweeter of disreputable Twitter accounts, and he’s floated all sorts of ridiculous conspiracy theories himself over the years – just ask Ted Cruz’s father, or Joe Scarborough. Trump fulsomely praised Greene upon her primary victory as a Republican rising star.

In 2017, Greene posted a long, hilariously earnest and completely bonkers explication of Q posts to YouTube. She had read them closely and spent time trying to figure out their import. The time and energy you’d hope an eventual congressional candidate would devote to understanding the federal budget or, say, how to reform military procurement, she’d poured into Q, and was clearly invigorated and alarmed by it.

And why not? A conspiracy theory has its pleasures. No matter how convoluted, a good conspiracy theory offers a relatively simple explanation of the world – namely, that it is controlled by a cabal.

A conspiracy theory lets its believers in on a secret not available to everyone else. It thus has the thrill of exclusivity; it bestows upon the initiated a knowledge ignored or dismissed by fools and the easily deceived.

A conspiracy theory offers the drama of a morality tale. Can the people with the discernment to understand and the willingness to fight back defeat the traitors carrying out a dastardly plot?

Q has a special draw for a segment of Trump supporters. The author’s lurid inventions involve people who are already villains of the populist right, the likes of George Soros and John Podesta. Q promotes a radical distrust of traditional sources of information and makes Trump’s stumbles into master chess moves, both of which are pleasing to Trump superfans.

All of this is an explanation, not an excuse. Q is deeply corrosive of the qualities necessary to live in and govern a republic. It invites its adherents to suspend reason – how else to credit all the prophecies that haven’t come to pass? – and believe that a swath of the American establishment isn’t just wrongheaded or incompetent, but engaged in monstrous secret crimes.

Marjorie Taylor Greene has already been criticized by Republican congressional leaders for her incendiary rantings about Muslims. She deserves, too, to be shunned her for attraction to Q, even if the president of the United States is unbothered by it.

Rich Lowry is on Twitter @RichLowry