"RE has been neglected. It is under-resourced," the Religious Education Council said. "Children, young people and society deserve better."
The council, representing RE teachers and major religions and denominations in England and Wales, is calling for a strategy to address the lack of expertise and training among RE teachers.
The situation, it said, has led to nearly a fifth of secondaries breaking the law by not offering RE to all 14 to 16 pupils. In sixth forms, well over a third of secondaries do not comply with the law and as a result trainee teachers often lack basic knowledge and understanding of the subject.
Community schools, in particular, struggle, but a few voluntary controlled primaries, mostly Church of England schools, provide more than pound;1 per pupil for RE and "even fewer" provide the legal 5 per cent of curriculum time in the subject.
"In many primary schools, there's great vitality in RE," Professor Brian Gates, chair of the council said. "The same is true in secondary schools, with the new popularity of take-up in GCSE and A-level. Elsewhere however, there's neglect."
Primary teacher training courses were providing "minimal" input on RE, the council said. Few primary teachers and fewer than half of primary RE subject leaders had any post-16 qualification in the subject, leading to a lack of high-quality teaching and low expectations.
In secondaries, standards were falling because there were fewer teachers qualified to teach RE than any other subject and many schools were failing to train and support those new to the subject.
The pressure on staffing was being exacerbated by the popularity of RE at GCSE and A-level.
The growth of the study of the ethics and philosophy of religion at A-level rather than of discrete religions was leaving trainee teachers with only a limited understanding of them.
On-the-job training was hampered by fewer than a quarter of local authorities having full-time RE advisers, the council said.
Department heads and RE subject leaders struggled to obtain funding for continuous professional development and a "worryingly high" proportion of teachers said "quick fix" online training was their only realistic option.
The majority of the extra pound;60 million would be spent on improving professional training over three to five years, with the Training and Development Agency for schools expected to fund improvements to initial teacher training.
The council wants the Government to look at ways of ensuring that all schools comply with law on RE. It also wants the brief of local Standing Advisory Councils on RE extended so they can share expertise with academies, voluntary aided, foundation and trust schools and community schools.