The Church of England is planning the biggest overhaul of its admissions code "in a generation" by urging schools to reserve no more than 10 per cent of places for followers of the faith.
Schools should not collect "nice Christians into safe places", but instead work with the wider community and open themselves up to more children from non-religious backgrounds, according to the chairman of the church's board of education.
The Rt Revd John Pritchard, Bishop of Oxford, said that admissions policies favouring religious children should be changed, even if accepting a broader range of pupils damaged results.
"I'm really committed to our schools being as open as they can be," Revd Pritchard told The TES. "I know that there are other philosophies that will start at the other end, that say that these are for our church families, but I have never been as convinced of that as others.
"Every school will have a policy that has a proportion of places for church youngsters . what I would be saying is that number ought to be minimised because our primary function and our privilege is to serve the wider community. Ultimately I hope we can get the number of reserved places right down to 10 per cent."
The Bishop's comments come ahead of guidelines on admissions to be published by the CofE during the summer. Around half of the church's 4,800 schools are voluntary aided, meaning they control their own admissions policies.
Revd Pritchard said he recognised that "in the real world" there were oversubscribed CofE schools that allocate high numbers of places based on religious observance.
The church cannot force individual governing bodies to change their admissions rules, but by issuing guidance it can put pressure on them to change. Revd Pritchard admitted that the move would not prove popular with all schools.
"I'm quite happy to have good, honest, robust discussions about what church schools are for," he said. "It goes back to what we see the mission of the church as being. I don't think the mission generally is about collecting nice Christians into safe places."
Revd Pritchard conceded the change might lead to lower exam results. "We may not get the startling results that some church schools do because of getting some very able children, but we will make a difference to people's lives," he said.
Professor Anne West from the London School of Economics, an expert on school admissions, said the guidance "could have the biggest impact on admissions to CofE schools in a generation".
"There will be quite a lot of concern at school level because it could drastically change the character of the schools in some cases," she said.
Revd Clive Sedgewick, director of education for the dioceses of Bradford and Ripon and Leeds, said any changes would have to be made slowly. "We have enough things with academies and free schools that we may be shooting ourselves in the foot to make massive changes in addition," he said. "Personally, I might suggest a third of places being reserved. There's a lot of debate to be had."
Revd Sedgewick said the move was likely to prove contentious with some parents. "There are parents that will see it as a retrograde step to have a higher number of non church attenders," he said.
The last Labour government attempted to guarantee 25 per cent of places at new faith schools for non-religious pupils, but was forced into a U-turn after lobbying by the Catholic church. New free schools with a religious character cannot reserve more than 50 per cent of places on faith grounds - still a much higher proportion than being suggested by the CofE.
Rabbi Dr Jonathan Romain, chair of the Accord coalition that campaigns for open admissions to faith schools, said the CofE was taking a "step in the right direction". "Those who object to it need to question why discrimination should remain a religious value in the 21st century," he said.
Original headline: C of E to throw open school gates to mass of non-believers