Pupils are being let down in RE lessons by ill-informed local syllabuses, the Office for Standards in Education reveals today.
David Bell, the chief inspector, said England's 150 RE syllabuses vary in quality between council areas, meaning many pupils receive sub-standard teaching and grades suffer.
"Some pupils are struggling to reach the required standards in RE," he said.
RE is compulsory but not part of the national curriculum. Instead, local councils have to form a Standing Advisory Council for Religious Education (Sacre), made up of church leaders, teachers and subject experts, to draw up syllabuses and oversee RE and collective worship in their schools.
Today's report shows many Sacres have difficulty recruiting people from minority religious groups. It says they are too divorced from the local authority and do not have clear development plans. They fail to check on RE teaching, are not focused on raising achievement and are not monitored properly.
"Very few syllabuses seen were of high enough quality throughout to make a consistently sound basis for good planning, teaching, learning and assessment," the report said.
The report, compiled following inspections of 19 Sacres across England, also criticises the organisations for failing to monitor daily collective worship in schools. Ofsted said earlier this year that as many as three-quarters of secondary schools flout the law on daily worship.
Today's report says that Sacres have had "limited success in persuading LEAs to make compliance a priority". Mr Bell said Sacres should adopt a new voluntary national framework for RE launched last month by Charles Clarke, the Education Secretary.
The framework follows growing concern over the patchy provision of the subject and recommends the teaching of humanism and minority religions, such as Jainism, alongside Christianity and other principal faiths.
The Professional Council for Religious Education (PCFRE), the organisation representing RE teachers, estimates that as many as one in five syllabuses is weak.
A TES survey earlier this month found that 92 per cent of Sacres agreed the framework was needed to raise standards. However, more than a third said that syllabuses would not be revised for at least five years. The Government has hinted that the framework may become compulsory if Sacres ignore it.
Guy Hordern, the chairman of Birmingham Sacre - which is responsible for 450 schools - criticised the teaching of secular views and said they should play no part in RE lessons.
Sacres were praised by Ofsted as worthwhile organisations allowing people of all faiths and ethnic groups an input into RE. And Ofsted said the best Sacres make a significant contribution to schools by offering services, leading worship and organising visits.
Criticism was also reserved for some LEAs that fail to provide Sacres with sufficient resources. Lat Blaylock, of the PCFRE, said Sacres suffered from lack of support from major teacher unions, including the National Union of Teachers, local councils and the Government. "In many areas Sacres are treated as oddities which don't receive appropriate support," he said.
The report, An evaluation of the work of standing advisory councils for religious education, is available at www.ofsted.gov.uk