Cynthia Dunbar does not have a high regard for her local schools. She has called them unconstitutional, tyrannical and tools of perversion. The conservative Texas lawyer has even likened sending children to her state's schools to "throwing them in to the enemy's flames". Her hostility runs so deep that she educated her own offspring at home and at private Christian establishments.

Now Dunbar is on the brink of fulfilling a promise to change all that, or at least point Texas schools toward salvation. She is one of a clutch of Christian evangelists and social conservatives who have grasped control of the state's education board. This week they are expected to force through a new curriculum that is likely to shift what millions of American schoolchildren far beyond Texas learn about their history.

The board is to vote on a sweeping purge of alleged liberal bias in Texas school textbooks in favour of what Dunbar says really matters: a belief in America as a nation chosen by God as a beacon to the world, and free enterprise as the cornerstone of liberty and democracy.

"We are fighting for our children's education and our nation's future," Dunbar said. "In Texas we have certain statutory obligations to promote patriotism and to promote the free enterprise system. There seems to have been a move away from a patriotic ideology. There seems to be a denial that this was a nation founded under God. We had to go back and make some corrections."

Those corrections have prompted a blizzard of accusations of rewriting history and indoctrinating children by promoting rightwing views on religion, economics and guns while diminishing the science of evolution, the civil rights movement and the horrors of slavery.

Several changes include sidelining Thomas Jefferson, who favoured separation of church and state, while introducing a new focus on the "significant contributions" of pro-slavery Confederate leaders during the civil war.

The new curriculum asserts that "the right to keep and bear arms" is an important element of a democratic society. Study of Sir Isaac Newton is dropped in favour of examining scientific advances through military technology.

There is also a suggestion that the anti-communist witch-hunt by Senator Joseph McCarthy in the 1950s may have been justified.

The education board has dropped references to the slave trade in favour of calling it the more innocuous "Atlantic triangular trade", and recasts the Israeli-Palestinian conflict as driven by Islamic fundamentalism.

"There is a battle for the soul of education," said Mavis Knight, a liberal member of the Texas education board. "They're trying to indoctrinate with American exceptionalism, the Christian founding of this country, the free enterprise system. There are strands where the free enterprise system fits appropriately but they have stretched the concept of the free enterprise system back to medieval times. The president of the Texas historical association could not find any documentation to support the stretching of the free enterprise system to ancient times but it made no difference."

The curriculum has alarmed liberals across the country in part because Texas buys millions of text books every year, giving it considerable sway over what publishers print. By some estimates, all but a handful of American states rely on text books written to meet the Texas curriculum. The California legislature is considering a bill that would bar them from being used in the state's schools.

In the past four years, Christian conservatives have won almost half the seats on the Texas education board and can rely on other Republicans for support on most issues. They previously tried to require science teachers to address the "strengths and weaknesses" in the theory of evolution – a move critics regard as a back door to teaching creationism – but failed. They have had more success in tackling history and social studies.

Dunbar backed amendments to the curriculum that portray the free enterprise system (there is no mention of capitalism, deemed to be a tainted word) as a cornerstone of liberty and argue that the government should have a minimal role in the economy.

One amendment requires that students be taught that economic prosperity requires "minimal government intrusion and taxation".

Underpinning the changes is a particular view of religion.

Dunbar was elected to the state education board on the back of a campaign in which she argued for the teaching of creationism – euphemistically known as intelligent design – in science classes.

Two years ago, she published a book, One Nation Under God, in which she argued that the United States was ultimately governed by the scriptures.

"The only accurate method of ascertaining the intent of the founding fathers at the time of our government's inception comes from a biblical worldview," she wrote. "We as a nation were intended by God to be a light set on a hill to serve as a beacon of hope and Christian charity to a lost and dying world."

On the education board, Dunbar backed changes that include teaching the role the "Jewish Ten Commandments" played in "political and legal ideas", and the study of the influence of Moses on the US constitution. Dunbar says these are important steps to overturning what she believes is the myth of a separation between church and state in the US.

"There's been this amorphous changing of how we look at religion and how we define religion within American history. One concern I have is that the viewpoint of the founding fathers is very clear. They were not against the promotion of religion. I think it is important to present a historically accurate viewpoint to students," she said.

On the face of it some of the changes are innocuous but critics say that closer scrutiny reveals a not-so-hidden agenda. History students are now to be required to study documents, such as the Mayflower Compact, which instil the idea of America being founded as a Christian fundamentalist nation.

Knight and others do not question that religion was an important force in American history but they fear that it is being used as a Trojan horse by evangelists to insert religious indoctrination into the school curriculum. They point to the wording of amendments such as that requiring students to "describe how religion and virtue contributed to the growth of representative government in the American colonies".

Among the advisers the board brought in to help rewrite the curriculum is David Barton, the leader of WallBuilders which seeks to promote religion in history. Barton has campaigned against the separation of church and state. He argues that income tax should be abolished because it contradicts the bible. Among his recommendations was that pupils should be taught that the declaration of independence establishes that the creator is at the heart of law, government and individual rights.

Conservatives have been accused of an assault on the history of civil rights. One curriculum amendment describes the civil rights movement as creating "unrealistic expectations of equal outcomes" among minorities. Another seeks to place Martin Luther King and the violent Black Panther movement as opposite sides of the same coin.

"We had a big discussion around that," said Knight, a former teacher. "It was an attempt to taint the civil rights movement. They did the same by almost equating George Wallace [the segregationist governor of Alabama in the mid-1960s] with the civil rights movement and the things Martin Luther King Jr was trying to accomplish, as if Wallace was standing up for white civil rights. That's how slick they are.

"They're very smooth at excluding the contributions of minorities into the curriculum. It is as if they want to render minority groups totally invisible. I think it's racist. I really do."

The blizzard of amendments has produced the occasional farce. Some figures have been sidelined because they are deemed to be socialist or un-American. One of them is a children's author, Bill Martin, who wrote a popular tale, Brown Bear, Brown Bear, What Do You See? Martin was purged from the curriculum when he was confused with an author with a similar name but a different book, Ethical Marxism.