Christian lobbyists are taking the government to court over plans to force independent schools to teach British values including "tolerance of those of different faiths".
The Christian Institute think-tank has declared the Department for Education's (DfE) plans will have "serious and perverse consequences" and is mounting a judicial review against the six-week consultation process as a result.
Former education secretary Michael Gove put forward proposals to force all schools to "actively promote clear British values" in the wake of the Trojan Horse plot, which revealed a number of Birmingham schools' involved in efforts to coordinate the teaching of Islamist views.
The government is introducing new standards requiring independent schools not to undermine the values of democracy, rule of law, individual liberty and mutual respect and tolerance for those with different faiths and beliefs.
Now they face a backlash from Christian activists who believe the changes will make it harder to impose religion on children in schools.
"This is a classic case of the government over-reacting to a perceived problem," the Christian Institute's chief executive Colin Hart said.
"They are shocking in their breadth and range and would destroy the independent sector.
"They mistakenly advance the principle that political correctness equals British values."
Hart said the changes would result in punishment for any school which has a "religious ethos, a set of traditional beliefs, or who don't over promote every minority group’s world view".
He added: "Under the plans, private schools, academies and free schools would have much less control over their ethos than ordinary state schools."
The government has denied the Institute's claim that the reforms would prevent teachers using gender-specific terms like 'mother' or 'father' – or that Christmas would have to be downgraded in independent schools.
"The Independent School Standards are designed to ensure every school prepares children for life in modern Britain," a DfE spokesperson said.
"We make no apology for demanding high standards and the promotion of tolerance and respect of all faiths and cultures."
Secularists believe parental demand is the driving force behind the enduring presence of religion in schools.
Many are now hoping the government's response to the Trojan Horse scandal could be used to roll back the influence of Christianity, in particular, on education in England and Wales.
"The Christian Institute has characteristically over-reacted to the government's proposals," Stephen Evans of the National Secular Society told Politics.co.uk.
"Throughout all aspects of education there should be an emphasis on the basic values that underpin a free, equal and progressive society.
"Schools have long been regarded by some as places where it is legitimate to promote and seek to instil particular religious beliefs in children and young people.
"The new standards start to address some of the worst excesses of that, so it's not surprising that those who want to use schools to promote their own dogmatic beliefs are resisting the changes."
Christians have been suspicious of the reforms ever since they were first unveiled by Gove.
"The answer is not to remove every reference of religion in school," the Church of England's new head of education, Nigel Genders, told TES in June.
"Children need to understand the different faiths in the world in which they live and you don’t do that by removing all references of religion."
The DfE is now considering its response to a letter from lawyers acting on behalf of the Christian Institute which states that the consultation breaks guidelines.
Only 30 schools – less than 0.5% of the total affected – offered responses to the consultation before it closed.
The changes require all independent schools to actively promote 'rights' in every subject.
"There was clearly a managerial problem in the schools in Birmingham, but is forcing more than 6,000 schools and over three million pupils to submit themselves to every whim of the PC brigade really the best way to tackle it?" Hart added.
"Patently not. So why is the government pursuing such an intolerant and aggressive agenda against a type of school they have actively promoted? It makes no sense."