The insurrection on Jan. 6 was the worst attack on the American system of government since the Civil War, and the telling of that story requires stronger stuff than HBO’s wet noodle of a documentary, “Four Hours at the Capitol.”

This disappointing film takes a both-sides approach to depicting that day, leaning heavily on interviews with the insurrectionists, whose most bizarre statements are unchecked. For example, we see a man, sitting beatifically on his couch, say, “800,000 kids go missing every year that are being held captive, killed and enslaved sexually.” Then, instead of refuting that statement in the strongest terms, director Jamie Roberts places a flattering chyron on the screen describing the man as an “Activist Filmmaker.”

This kind of treatment continues throughout. One man announces that Donald Trump was “anointed by God”; another calls him his “savior.” Yet another man refers to “a lot of fighting between patriotic people and the Capitol Police”; another claims that “the American spirit” was “on display” when the violent mob attacked the Capitol.

The documentarians hear all this and don’t blink an eye. They give a platform for these sentiments and confer dignity on those presenting them.

The most generous interpretation of HBO’s approach here is that the people behind the film simply assume that such statements are so outlandish that they don’t need to be refuted, that everyone who watches the film will know they’re inaccurate or untrue. But if the filmmakers actually believe that, what country have they been living in for the past five years? If they’re so fundamentally misguided as to assume Americans are driven by facts and rationality, they don’t have a basis for understanding what happened on Jan. 6.

The documentary, available on HBO and HBO Max starting Wednesday, Oct. 20, begins as it should, with Mike Fanone — a Metropolitan Police officer who was beaten and tased by the insurrectionists — talking about leaving for work on that morning. But it quickly shifts to telling the story from the standpoint of the insurrectionists. The film contains a lot of footage from inside the riot, with people shouting things like, “Protect the Constitution,” and, “Don’t go against the United States,” even as they’re trying to subvert the most foundational of constitutional processes and are attacking the seat of government.

The documentary also makes use of the police officer’s body cameras at length and to such an extent that you get a sense of the hand-to-hand battle that took place for hours. It looks like medieval combat out of “The Last Duel.”

But anything useful in “Four Hours at the Capitol” is undermined by its treatment of the insurrection as a family disagreement between equally sincere and reasonable opponents. This is not just wrong, it’s irresponsible. Imagine if months after 9/11, there was an HBO documentary featuring friendly interviews with terrorists talking about how happy they felt when the planes hit the buildings. That would have been outrageous, and yet in one way, “Four Hours at the Capitol” is worse than that. It gives voice to lies that have gained traction among a sizable minority of the public.

I can anticipate the counterargument: There’s a virtue in subtlety. Why not let the point slowly emerge? Why hit people over the head?

The answer: There’s no point in being subtle when some people are literally hitting people over the head. We’re beyond the need for subtlety. A documentary that doesn’t have the stomach to tell the story of what happened on Jan. 6 explicitly, and to express the real threat to American democracy that that day represents, is of no use to anybody.

K“Four Hours at the Capitol”: Documentary. Directed by Jamie Roberts. (TV-MA. 92 minutes.) Premieres at 6 p.m. Wednesday, Oct. 20, on HBO and HBO Max.