Don McLeroy, chairman of the Texas State Board of Education from 2007 to 2009, is a "young earth" creationist. He believes the earth is 6,000 years old, that human beings walked with dinosaurs, and that Noah's Ark had a unique, multi-level construction that allowed it to house every species of animal, including the dinosaurs.

He has a right to his beliefs, but it's his views on history that are problematic. McLeroy is part of a large and powerful movement determined to impose a thoroughly distorted, ultra-partisan, Christian nationalist version of US history on America's public school students. And he has scored stunning successes.

If you want to see a scary movie about this movement, consider taking in Scott Thurman's finely-crafted documentary Revisionaries, currently making the festival circuit, which records the antics of McLeroy and a hard right majority on the Texas State Board of Education (SBOE) as they revise the textbook standards that will be used in Texas (and many other states).

The first part of this documentary deals with the familiar "science wars", in which one side seeks to educate children in the sciences, and the other side proposes to "teach the controversy" in order to undermine those aspects of science that conflict with its religious convictions. But it's the second part of the movie where the horror really kicks in. As I explain in more detail in The Good News Club: The Christian Right's Stealth Assault on America's Children, the history debate makes the science debate look genteel. While the handful of moderates on the SBOE squeals in opposition, the conservative majority lands blow after blow, passing resolutions imposing its mythological history on the nation's textbooks.

Cynthia Dunbar, a board member who has described public education as a "subtly deceptive tool of perversion", and who homeschooled her own children, emerges as a relentless ideologue. During the hearings, she yanks Thomas Jefferson from a standard according to which students are expected to "explain the impact of Enlightenment ideas … on political revolutions from 1750 to the present", and replaces him with the 13th-century theologian St Thomas Aquinas. Moderate Republican board member Bob Craig points out that the curriculum writers clearly intended for the students to study Enlightenment ideas and Jefferson in this part of the standard, not a mix of Protestant and Catholic theologians, but the resolution passes anyway.

Dunbar isn't very subtle about her agenda. In one scene, the filmmakers track her to a prayer rally in Washington, DC, where she implores Jesus to "invade" public schools.

The board goes on to remove the word "slavery" from the standards, replacing it with the more benign-seeming "Atlantic triangular trade". They insist on calling the United States a "constitutional republic" rather than a "democracy" – largely because they want students to think of their country as Republican, not Democratic. So convinced are they of the timeless superiority of American/Republican values that one of them introduces a standard asking students to "explain three pro-free-market factors contributing to European technological progress during the rise and decline of the medieval system".

Historical figures of suspect religious views (like Jefferson, Thomas Paine, Benjamin Franklin) or political tendency (like union organizer Dolores Huerta) are ruthlessly demoted or purged altogether from the study program. Meanwhile, the board majority makes room for an eclectic array of ancillary figures from the revolutionary period, such as Charles Carroll and Jonathan Trumbull. What these marginal figures have in common, other than being dusted off from high shelves and promoted by the board, is the fact that they were loud defenders of orthodox Christianity.

Even by their own admission, the board members were hopelessly unqualified to make judgments about the history. So they appointed a committee of academic "experts" to vet the standards. The committee was a model of "bipartisanship" in the modern era. For their part, the moderates on the board appointed credible historians, professors at Texas universities; one was defended by a moderate Republican board member as "a good Republican … not some kind of crazy liberal".

The conservatives, on the other hand, appointed Peter Marshall of Peter Marshall Ministries, a group that seeks to "reclaim America for Christ" and is "dedicated to helping to restore America to its Bible-based foundations through preaching, teaching, and writing on America's Christian heritage and on Christian discipleship and revival". They also appointed pseudo-historian David Barton, the former vice-chairman of the Texas GOP and founder of the Black Robe Regiment. The latter, sinister-sounding organisation is an association of "concerned patriots" whose goal is to "restore the American Church in her capacity as the Body of Christ, ambassador for Christ, moral teacher of America and the world, and overseer of all principalities and governing officials, as was rightfully established long ago".

Barton is known for fabricating quotes from America's founders, or taking them out of context to build his case that America was established as a so-called "Christian nation". And here's the gruesome kicker: the Texas board actually ignored advice from its own, balanced committee whenever it contradicted the agenda of the far-right majority.

Sometimes, the most important characters in a story are the ones who don't show up. In the Texas battle over history, the heroes who went missing were the kind of people and organizations that might have defended the teaching of history in the way that the scientists mobilized to defend the teaching of biology. The scientists are reasonably well-organized. When creationism rears its paleolithic head in state legislatures or on school boards, it faces the opposition of organizations such as the National Association of Biology Teachers, the American Association for the Advancement of Science, the National Center for Science Education, the American Institute for Biological Sciences, the National Association of Geoscience Teachers, the National Earth Science Teachers Association, and others.

Defenders of biological sciences can also fall back on court rulings such as Kitzmiller v Dover Area School District and Edwards v Aguillard, which prohibit teaching of creationism. They also have a wealth of popular treatments of scientific issues to draw upon, such as explanations of evolutionary theory by Richard Dawkins and other scientists.

History, however, is often left to fend for itself.

To be fair, in the Texas proceedings, some historians and activists made valiant attempts to contain the damage. Kathy Miller, spokesperson for the Texas Freedom Network, an Austin-based research and advocacy group, was allocated several minutes for her impassioned defense of religious and political neutrality in public education. Professor Steven K Green, director of Willamette's Center for Religion, Law, and Democracy, used his five minutes in front of the board to remind them that "the supreme court has forbidden public schools from 'seeking to impress upon students the importance of particular religious values through curriculum.'" The board majority smiled and looked away.

So, where are history's defenders?

Part of the problem here has to do with a common fallacy about history. We think of history as a "soft" subject. We know that it always involves some degree of interpretation, that the "narratives" are always "contested", and that the answers are never so obviously right or wrong as they are in science. We also know that there have been leftwing versions of the history that are just as distorting as the rightwing propaganda served up by McLeroy and friends. But it's plain wrong to think that we can only throw our hands in the air and conclude that history is whatever anyone chooses to say it is.

Some academics have gotten too used to speaking only with one another. Many could do a more forceful job of seeking to protect the public from disinformation. When I was researching my book, I came across plenty of academic historians who were dismissive about David Barton in private; but few were willing to go public, or to invest the effort in refuting him in detail.

Barton recently came out with another piece of propaganda, The Jefferson Lies: Exposing the Myths You've Always Believed About Thomas Jefferson. To their credit, a pair of professors who identify themselves as conservative Christians, Warren Throckmorton and Michael Coulter, have stepped forward to debunk Barton's latest exercise in their book, Getting Jefferson Right: Fact Checking Claims About Our Third President. But that hasn't stopped Barton's book from becoming a bestseller.

Maybe, we find it easy to underestimate the harm that bad history can do. McLeroy and his cohorts desperately want students to be taught that America is beyond criticism. It's greatness, they believe, stems from the values, principles, and methods of America's conservatives, and the only safe path to the future is to suppress or eliminate whatever does not conform to their image of a purified America. These "revisionaries" are far from the vision of the US bequeathed by the same founders whom the far right claims to revere.

The "glory of the people of America" as James Madison actually said, is that they broke free from the "blind veneration" of the ways of the past and learned how to draw on the "lessons of their own experience" in order to build the world anew.