Children should attend church at least twice a month to get a place at a popular Anglican school, according to the Church of England's head of education.
The transparent "test of faith" is needed to give parents a much clearer understanding of what is required to attend the most oversubscribed church schools, said Canon John Hall.
His comments follow recent criticism that some schools employ over-elaborate points systems to gauge whether children are suitable. Some rate children by the number of times they attend a service, others attribute points to families who help out at the local church, and some ask for letters from clergymen.
Now the CofE is preparing to issue guidance to more than 4,500 of its schools clarifying how governors should judge religiosity. It is intended to add teeth to the Government's proposed new admissions code, published last month, which says faith schools should clearly outline "how religious affiliation or commitment is to be demonstrated".
In a speech to the Association of Anglican Secondary School Heads annual conference last week, Canon Hall suggested that attendance at church twice a month should act as a basic test of religious observance when parents are attempting to win a reserved faith place at a popular church school. He also said schools should not discriminate between parents who are core members of the church and those who are simply known to it.
"We want a system that is transparent, easily understood and as straightforward as possible," he said. "We have been thinking how we can offer guidance that would encourage schools to simplify their practices. We are quite alarmed at the highly elaborate points systems some schools use that parents find quite impenetrable."
If faith schools are oversubscribed, they can reserve a certain number of places for children from religious families, stipulating in their admissions rules how religious observance is to be judged. A proportion of additional places are often also reserved for pupils who live near the school, regardless of their faith. But critics said it would not address the problem of middle-class parents monopolising church schools.
Church congregations have declined by 50 per cent in 25 years, with fewer than 7 per cent of the population attending church on Sundays, according to the English Church Census, published earlier this month.
Chris Waterman, executive director of Confed, which represents education directors, added: "Regularity of church attendance within a prescribed period is easy to manipulate."