Church of England expansion under fire
The Society, whose honorary associates include the playwright Harold Pinter and the zoologist Richard Dawkins, claimed religious schools hampered rather enhanced community and race relations.
"We can see some inkling of the future from the effect of sectarian schooling in Northern Ireland," said Keith Porteous Wood, the society's general secretary.
He hit out as a review group, set up by the Archbishops' Council, met for the first time this week to begin what may herald the biggest shake-up in Christian education in Britain for 30 years.
The review, chaired by Lord Dearing, is charged with looking at the opportunities to increase the number of church schools - particularly secondaries.
Its work comes as the number of children attending Sunday school plummeted this year to a predicted 530,000 - or 4 per cent of the child population.
At its peak, in 1905, Sunday school attracted 7.09 million chldren, 56 per cent of the child population. Numbers declined steadily throughout the century, dropping to around 1m in the 1980s.
The churches pay 15 per cent of voluntary-aided schools' capital costs and the Church of England and Roman Catholics each spend around pound;10m annually on their schools.
The Church of England provides one primary school in four and one secondary in 20, educating 900,000 pupils. It is now looking at taking over failing comprehensives and building secondaries.
But the Secular Society, founded 134 years ago, said that, instead of opening more church schools, efforts should be concentrated on improving mainstream education for all pupils.
Mr Porteous Wood said: "The very concept of pupils being selected with reference to their parents' beliefs (including their perceived piety or lack of belief) is abhorrent in the 21st century.
"Religion being taught as fact amounts to indoctrination which should have no place in schools funded by the whole community, including those who do not subscribe to religion."