Earlier this month, the Christian Institute released details of the unnamed independent school in the Home Counties that has been told it isn't adhering to new rules by not inviting a member of a different faith to conduct an assembly.
New rules regarding the promotion of British values were brought in following the 'trojan horse' scandal, which saw several Birmingham schools accused of trying to introduce an Islamist ethos.
Speaking on Premier's News Hour, Simon Calvert from the Christian Institute said the treatment of the school was unacceptable: "Nobody can accept all faiths.
"Should everybody accept Scientology? Or should we be able to say, 'Actually, we think it's profoundly wrong.'
"That's the problem with this vague, warm and fluffy wording that we're getting from the Department of Education.
"What we need is for them to go back to the drawing board and talk to the faith schools."
The issue was brought up in the House of Commons by Christian Tory MP David Burrowes.
In a question to the Education Secretary, the MP for Enfield, Southgate, said: "There are reports that Ofsted is demanding that a Christian school invites an imam to take collective worship and that Jewish schoolchildren have been asked intrusive questions about their views on sexuality. Does that really promote British values?"
Nicky Morgan responded: "I thank my honourable friend. That is clearly a matter for Ofsted and it is investigating exactly what was said to the school. I think we would all agree that the fundamental British values of respect, democracy and tolerance are shared by all schools and all people of all faiths."