Major spoilers for It Chapter Two ahead! Pennywise the Clown seems invincible — even the Losers Club can't destroy him the first time they try. And yet, there is one possible way to stop It. Stephen King fans who've read his 1986 novel It are already familiar, but those who only know the Maine town of Derry through the movies may be a little confused by the Ritual of Chüd and how, exactly, it stop a killer clown who's been terrorizing a town for centuries.
You might have seen a flurry of articles across the internet excitedly exclaiming It: Chapter 2 would feature "the weirdest element from the book", or "one of the book's weirdest scenes". No, it's not the excised child orgy where the Losers lose their virginity to Bev in the sewers (seriously, a Thing That Happens in the book to "reunite" the team) that was cut for some reason from the first film. They're referring to the book's other bonkers bit, the bizarre Ritual of Chüd.
In the novel, the ritual is a multidimensional, metaphysical test of will, but its discovery, description, and way it's executed are...well, odd to say the least, even for a horror novel. Bill learns about the ritual through an ancient inter-dimensional turtle named Maturin (likely the Turtle referred to in King's Dark Tower series), who tells him what to do. Bill must challenge It by overlapping and biting down on both their tongues to begin a joke-telling contest, where whoever laughs first, loses.
When the Losers finally confront It, It's taken the form of a giant spider, impossible for them to physically defeat, but possible to challenge psychically. When Bill does so, he's taken to a place beyond time and space, possibly where the deadlights were created, and fights It mentally while his body remains locked in place under Derry. He's not literally biting down on It's tongue, but rather the tongue in both their minds, not that that's less strange. Bill performs the ritual twice, once as a kid, when he manages to weaken It, and again as an adult when he weakens It again to the point the Losers can physically kill It.
In the film adaptation, 2017's It, there's no mention of psychic World Turtles or the ritual — the gang confront It after Beverly's kidnapped and fight it to the point of retreat. Talking to CinemaBlend, It screenwriter Gary Dauberman explained the absence, and told fans they could expect to see the ritual come Chapter 2. "The Ritual of Chüd is challenging, but it's such an important component to the book that we had to address it...it's really kind of just chipping away at the stone and trying to find the most focused, accessible way into some of more metaphysical aspects of that book."
The film's first mention of the ritual integrates more easily into Derry's fictional reality, as opposed to King's multi-novel, multi-dimensional battle between good and evil centered in books like The Dark Tower series and The Stand spilling into It via psychic turtle pep talks. Out of all the Losers, only Mike Hanlon has (Isaiah Mustafa) remained behind, and only he remembers what happened. In the years since, he's obsessively researched It's history, looking for a way to destroy It once and for all, while warily monitoring for signs of It's return.
He shows Bill (James McAvoy) — and the audience — the results of his search: a Shokopiwah tribal artifact, given by (well, stolen from) Shokopiwah that originally lived where Derry now stands. (The tribe itself is fictional.) There's also a small helping of a Shokopiwah "herb" that aids both Mike and Bill in "seeing" (vision-quest style) what happened in the past. Knowing about It, the tribe moved beyond where It could attack them, but attempted the Ritual of Chüd to destroy it. The images on the leather box show a group holding hands as a destroying bird dives down to attack them, a fire with three glowing orbs (the deadlights) above it, and a mysteriously blank side.
The ritual remains a psychic battle of wills, but instead of a one-on-one challenge, each member of the Losers has to gather their own artifact, something that will force them to confront something they'd rather forget, but which embodies something they'll want to hold on to, if they let themselves remember. In It's deepest inner sanctuary, the group burns the objects, symbolically overcoming their own pasts and uniting as one to draw down and face It. Firm belief is key to the ritual's success — when Bev (Jessica Chastain) hands a weapon to Eddie (James Ransone) and tells him it kills monsters "if you believe it does", that's the kind of strength the Ritual of Chüd requires. The Shokopiwah failed, but Mike is convinced the Losers can succeed, if they believe they can.
And that's the essence of Chüd, a childlike belief and trust, often lost as people age and face life's pangs, paired with sheer will and pitted against a monstrous force bent on corrupting and undermining exactly those qualities through fear. And that's the theme of It — that childhood and adulthood can and need to coexist.