Among the Believers, a chilling new documentary that premiered at the Tribeca Film Festival, opens on a terribly cute 5-year-old boy. His father has just abandoned his mother, leaving him alone in the world, so he’s turned to Abdul Aziz Ghazi, known to his acolytes as Maulana Aziz.

“What do you want to be when you grow up?” the cleric asks.

“A mujahid.”

“Do you remember those sermons we taught you?”

The little boy stands up, and unleashes a big smile.

“I seek Allah’s refuge from Satan. I begin with the name of Allah the most merciful. Look at the sacrifices of the martyrs of the Red Mosque.” His calm demeanor turns violent, as he begins yelling and shaking his miniature fist in the air. “We will destroy you if you attack us! You cannot enter here! You cannot conquer us! You cannot! And if you dare to enter here we will destroy you in the name of jihad!” With that, the little one smiles, and turns to the cleric, seeking paternal approval.

“Well done.”

Directed by Hemal Trivedi, a Hindu from India, and Mohammed Ali Naqvi, a Pakistani Muslim, Among the Believers chronicles five years behind the walls of Lal Masjib (Red Mosque), a controversial madrassa in Islamabad, Pakistan, that prepares Muslim children as young as 5 for jihad. It’s the home base of the Red Mosque Madrassa Network, which comprises 30 schools and an army of 10,000 students spread across Pakistan.

Built by the government in 1965, and named for its red interiors, the Red Mosque made front-page headlines when, on July 3, 2007, a bloody standoff ensued between students barricaded inside the mosque and Pakistani police, who accused members of the mosque of everything from kidnapping and murder to terrorism. A shootout commenced, and 20 people were killed. Amid the carnage, Maulana Aziz was arrested by Pakistani authorities as he was trying to flee the scene in a burqa, and immediately after, in a truly surreal moment, was paraded in front of live news cameras and forced to remove the burqa in front of a nationally televised audience.

“He lost credibility, but he also gained credibility,” co-director Hemal says. “Looking at the way he was publicly humiliated, other people said, ‘Look at what happened to him! If we surrender, we’ll be humiliated, too.’”

On July 10, 164 troopers from the Pakistani Army stormed the Red Mosque, killing an estimated 50 jihadis But the government intervention only seemed to strengthen public support for their cause, with Ayman al-Zawahiri, al Qaeda’s former longtime No. 2—and the group’s leader since the death of Osama bin Laden—releasing a video message on the raids saying, “Your salvation is only through jihad.”

The Red Mosque also has named its central library after bin Laden and, on November 29, 2014, the extremist all-girl students of Jamia Hafsa, a madrassa in the Red Mosque Network, released a video in support of ISIS, urging all Pakistani jihadis to join forces with the terrorist organization. Maulana Aziz refused to condemn the video, instead remarking, “I don’t know why these boys are reluctant to say that we support the organization which wants to implement the Islamic system.”Then, on December 16, 2014, seven Pakistani members of the Taliban attacked the Army Public School in Peshawar, Pakistan, massacring 132 schoolchildren in what remains the deadliest terrorist attack in the history of Pakistan. Maulana Aziz also refused to condemn that attack, leading to massive protests against the Red Mosque.

“It was only until the Peshawar attack where the tide started to turn, and almost everyone in Pakistan condemned those terrible attacks, and the Red Mosque for not condemning them,” says Mohammed.

Inspired by the Mumbai terror attacks, carried out by militant Pakistani Muslims, which claimed the life of one of her closest friends, Hemal began shooting footage for Among the Believers in 2009. Since she’s an Indian woman, she went to the madrassa disguised as “Hanna Khan,” a Pakistani Muslim from Dubai. She said she got access to shoot there a few times, but was soon tipped off that she was “being watched.” She needed a Pakistani Muslim to gain access, so in stepped Mohammed, a mutual friend.

According to Mohammed, the crew got access to interview and shadow Maulana Aziz through the film’s co-producer, Syed Musharraf Shah, who comes from a conservative Pakistani Muslim background, and has loose ties to the Red Mosque. It took the filmmakers a while to build up trust with Maulana Aziz, so the bulk of the footage inside the mosque was shot in 2013 and 2014. They were not, however, allowed to film any female members of the Red Mosque.

“He’s pretty narcissistic,” Mohammed says of Maulana Aziz. “If you look at all his interviews they’re all the same sermons, but we wanted to know what it was really like at the mosque.”

The film spends the bulk of its time trailing two 12-year-olds. One, a girl named Zarina, escaped the Red Mosque by jumping over a stone wall, leaving her burqa behind. She said the girls were fed “one slice of bread a day” and were beaten if they set foot outside the mosque’s walls.

“I am scared. What if they come here? They don’t want peace. They just want to kill. They will never let anyone live in peace. They are not Muslims. They are infidels,” says Zarina.

After her escape, she moved back with her family in a destitute village on the outskirts of Islamabad, delighting in attending a progressive school funded by an American NGO consisting of Pakistani ex-pats. But unlike the palatial Red Mosque, the school faced numerous funding issues and was forced to close its doors. Left with no choice according to custom, Zarina’s parents forced her to marry at 14.

“Pakistan is a deeply divided country,” says Hemal. “There’s a fringe minority of extremists who are taking over the majority of moderate Pakistanis, and the Pakistanis’ way of life is under threat. The biggest battleground in Pakistan is in the area of education. It’s a battle for children’s minds.”

The other child is Talha, who is on the opposite end of the spectrum. He becomes very invested in the Red Mosque—to the horror of his parents, who desperately want him to leave, worried that he’s becoming too extreme and myopic in his beliefs. “I get to go home once a year,” says Talha. “They wake us up a half-hour before dawn. Then we memorize the Quran until we go to bed at 9 p.m. All this hard work will pay off when we die. We will go to heaven and wear a special crown.”

Despite the extremism of his teachings, the film provides as balanced a portrait as possible of Maulana Aziz, blaming larger systemic problems within the Pakistani government and economy, which has largely failed its people, for creating the vacuum the radical cleric occupies.

“We wanted to give him his fair due,” Mohammed says. “If you wanted to make a polemic on Islam and show a crazy, bearded dude who’s frothing at the mouth and declaring jihad everywhere, you can go to Fox News and go see that.”

One of the funnier scenes the filmmakers witnessed—which they say is saved for the DVD—concerns Maulana Aziz’s DVD stash. While the Red Mosque allows children to imbibe only the Quran, banning all other aspects of culture from chess and books to television, Maulana Aziz apparently has quite the collection of DVDs, from feature films to Planet Earth and National Geographic documentaries. A chuckling Hemal and Mohammed recall watching Maulana Aziz re-editing a documentary on ocean life.

“It was re-dubbed to say, ‘Look at this starfish and its beautiful spots that Allah made’ or ‘look at this fish and the way it moves, Allah made it move like this,’” says Mohammed.

“It’s total mind-control,” adds Hemal.

In another chilling sequence, a cleric at one of the Red Mosque Network of schools delivers a tour of the cramped surroundings. He gestures to a group of children, who can’t be older than 10 years old.

“They’re really malleable at this age,” he says. “The way you mold them now will shape them for life. Once we train their minds, they’ll never change until they die.”