Clearer guidelines must be introduced to establish which religious organisations will be permitted to take up the running of state-funded faith schools, a teachers' union says.
There was currently no clear indication of who would approve or reject an application to build a school called the Osama Bin Laden Academy, warned the general secretary of the Association of Teachers and Lecturers (ATL), Peter Smith.
Similarly the Church of Scientology, the Moonies or even supporters of David Icke - the former footballer and TV presenter who once claimed he was the Messiah - could apply to run a state school, said Mr Smith.
Since the attacks of 11 September, race riots in the north of England last summer and tension surrounding a Roman Catholic school in Belfast, government plans to encourage a wide range of religious groups to run state-funded schools have proved controversial, with critics saying they are divisive.
Mixed opinion over faith schools was no less obvious than at the ATL's annual conference in Cardiff, where delegates tabled conflicting motions on the matter.
One calls for the government to abandon all plans to increase the number of faith schools, another urges delegates to "recognise the positive contribution these faith schools make to the education of young people".
'Reservations'
But the ATL's general secretary, Peter Smith, said the union had "grave reservations" about how the faith school policy was being implemented in communities.
"The problem for the government is what we do about religious groupings, that are often heavily bankrolled, that come along and say they want to open a school?
"Suppose there was an application to open the Osama Bin Laden Academy – who exactly would say 'no' and on what justification?" asked Mr Smith. Faith schools must give pupils a full and equal access to the national curriculum, he said.
'Snoring dog'
And those which did not admit girls as well as boys, and pupils from other religious backgrounds, should have their funding withdrawn, he added. The ATL was not pressing for a secular education system, said Mr Smith, as history could not be rewritten.
But he said the government had made a grave mistake when it paved the way for more faith schools.
"My own personal view is if a dog is snoring, don't kick it awake and I think it was very stupid of the government to kick this dog awake," he said.