“Let’s thank the heroes who struggled to make our country a democracy.”

In the autumn of 1965, a group of military officials in Indonesia staged a coup in a purported attempt to save the country from radical communists. Within days they had subdued the radicals; within weeks they had organized hit squads to search out and attack other communists, intellectuals, and ethnic Chinese; within months they had murdered about a million people. By the following summer, the .new regime was firmly entrenched, and its leaders set about with the next step, the winners’ prerogative: writing the history books. In the official account, the purge victims became godless terrorists; their executioners became heroes and patriots. Many of the men who disemboweled suspected communists by the banks of the Snake River are now popular political figures.Make no mistake—‘The Look of Silence’ is not fun. It is, however, essential.

Some survivors of the ’65-’66 purges are still alive today as well. They don’t talk very much about the horrors they witnessed during that time, though. After all, they live in villages alongside soldiers, mayors, and schoolteachers whose hands once wielded rifles and bloody machetes. Who could blame them for keeping silent?

Given this societal climate, an Indonesian citizen who’s willing to break the silence to ask dangerous questions is an utterly singular sort of person. There’s nothing obviously special about Adi, the hero (a word I use advisedly) of the haunting new documentary The Look of Silence. He works as an optometrist in a semi-rural area. He goes to work every day, visits his elderly parents, and horses around with his young daughter. But he does have at least one distinction: his older brother, Ramli, was one of the suspected dissidents butchered by government-sanctioned thugs, and Adi wants to have a word with Ramli’s killers.

“I ripped him open and his intestines spilled out. I cracked open his skull; he tried to hold his head together with his hands.”

Over the course of the film, Adi meets with some of the people responsible for his brother’s murder, and every encounter plays out similarly. Quietly but directly, Adi confronts them about their role in the deaths of Ramli and the countless others like him, and these men in turn affirm their participation. To viewers who are used to circumlocutions and evasiveness from heavily scrutinized public figures, it’s quite a shock to watch these people openly—and in some cases proudly—admit their involvement in such violence. Not since Nuremberg have we had such an unvarnished, firsthand record of individual depravity working in harmony with institutional brutality.

It is impossible to convey how frightening it is at times to watch this documentary—it must be seen to be believed. The viewing experience is simultaneously riveting and repulsive, almost like one of those nightmares in which you want to run away but are rooted to the spot. One man chuckles as he recounts maiming his prisoners in unspeakable ways; another expresses regret only at the realization that he forgot to bring a prop weapon to demonstrate his “techniques.” When the man who personally killed Ramli talks about how he would literally drink his victims’ blood in obedience to a local superstition, I felt as if I were being pressed backward into my theater seat.

Make no mistake—The Look of Silence is not fun. It is, however, essential. Director Joshua Oppenheimer, like a Virgil of the movies, guides us closer than many of us have ever been to the squirming heart of human evil. Oppenheimer does not find monsters there—Indiana-Jones villains with black uniforms and scary voices. It would almost be easier if he had. All he finds are people who don’t even reach for the Eichmann-like “only following orders” defense. They did what they thought was right. They’d do it again.

“If we didn’t drink human blood, we’d go crazy. . . . If you drink blood, you can do anything.”

The Look of Silence is essential because its subjects demonstrate just how easy it is to abstract evil into something that is domesticated and unremarkable. Hannah Arendt wrote of the banality of evil, but the murderers Adi meets are not the dull-minded bureaucrats of Arendt’s Eichmann in Jerusalem. Rather, they were in the thick of things, fully attuned to the mechanics of slaughter. They were not just putting in a day at work; they were mixing business and pleasure. In Oppenheimer’s telling, there’s some other ingredient to the special depravity of large-scale killing—something that is simultaneously horrifying, confusing, absurd, and all too human.

The ineffability of this phenomenon is dramatized in a scene late in the film. Adi’s mother is sitting on the ground, holding a couple of nuts in her open hand. Similar to Mexican jumping beans, the nuts quiver and rock in her palm as the insect larvae gestating within them move about. Adi’s mother gazes intently down at them. “Where are you?” she says to them, quietly. “I don’t see you. I know you’re there.”

“We should be rewarded with a trip to America.”

It’s tempting to see The Look of Silence (and its companion piece, 2013’s superb The Act of Killing) as yet another portrait of political violence in a developing nation. We may have seen many such documentaries (albeit none so unflinchingly disturbing)—so many that our reflexive response very well might be jaded mournfulness. How awful for them, we might say. Political stability, social justice, and the gospel will fix them right up.

Let us not make the mistake of condescending to these people, as if we and our country are innocent of similar crimes. We the people of the United States would rather forget that our country is constructed on the bedrock of a slave trade that built an economic empire of cotton and drank the lives of millions. Our foundations were laid on the corpses of Africans; our borders were expanded through the corpses of Native Americans. Our zeal for the cause of democracy inspired others to create many more corpses. And now we learn that our own government has been freely torturing its enemies—half-drowning them, breaking their bones, keeping them awake until they go insane.

It’s enough to make you wonder what documentaries will be made about us in fifty years.

But leave aside, for now, the question of collective national guilt. Consider again the image of those jumping beans: twitching and rocking to and fro, animated by a creature inside that is unseen but no less real for it. You and I have felt this larval stirring in our hearts, as our greed or bigotry or pride curls in on itself and feeds. We may not want to think about these things in the midst of the joyous season of Advent, but we must. We must not forget that the coming of our Savior was accompanied not by well-mannered silence but by loud cries, and that some of those cries came from Rachel weeping for her slaughtered children. We must not forget the voice that cried out in the wilderness. The owner of that voice had one message for the people of his day: Repent.