The school's pupils come from a variety of backgrounds
Raine's Foundation School in east London is a Church of England school which already does just that.
Raine's reserves 75% of its places for children from families adhering to the major Christian faiths - with priority going to the Church of England.
But a quarter are for children of other faiths or no faith, with priority going to other "world faiths".
In practice this means Muslims, Sikhs and Jehovah's Witnesses. There are very few of no faith.
Ethnically the result is that pupils are 45% black, 45% white and 10% of Asian origin.
The head teacher, Paul Hollingum, said the school's governors had thought it important that it reflect the community of which it was a part.
Good proportions
He said the three quarters church majority was enough to maintain the school's ethos.
"I shouldn't really be speaking for the bishops or the diocesan boards," he said, "but for me, as a head, I'm delighted that I am in a school where 25% of the population are not from a Christian background."
More than that might dilute a school's character, less could be too insignificant, so it was about right, he said.
The school has two applicants for every Church place - it is 10 to one for the other faiths - and the effect of the admissions rules is that families with Church backgrounds are turned away.
"Parents are not very happy," Mr Hollingum said.
"They feel we have let them down. They don't necessarily understand that as a Church school we do want to give places to people from other than Church families."
Church schools had a very clear ethos and people knew what they were "buying into".
"They have chosen a school which has got a moral character which is fairly clear, and even if they are not from a religious family they do understand what we stand for."