Brian Gates, chairman of the Religious Education Council of England and Wales, said weak teaching had created a culture of "ignorance" among thousands of teenagers, turning many towards misguided beliefs.
His comments come as the Qualifications and Curriculum Authority prepares to release a series of new teaching modules in the autumn to accompany the first national RE framework.
The framework, drawn up after talks with all major faith groups in England and Wales, was published last year amid growing concerns about RE. Charles Clarke, then education secretary, said it would be accompanied with further reforms, including more RE teachers, better in-service training and new classroom materials.
Lord Adonis, the school standards minister, who is overseeing future policy developments in religious education, will meet the RE Council next month.
The council said anti-Islamic sentiments following the London bombings underlined the need for a rapid improvement of RE in schools.
Professor Gates said: "I am in no doubt that if there had been a richer RE provision over the past 10 years our communities would be wiser than they are at the moment.
"Some of the RE being taught in our schools does nothing to challenge the ignorance that prevails in certain parts of society.
"Evidence shows that when RE is well-resourced and well-taught children are better informed, and generally more appreciative of diversity and other faiths."
RE is compulsory in state schools, unless parents ask for their children to opt out, but the subject is not part of the national curriculum.
Last year Ofsted said that the 150 locally-produced syllabuses in England had varied hugely in quality, meaning that many children had received sub-standard teaching.
The framework recommends the teaching of minority faiths and secular philosophies alongside Christianity and other principal UK religions.
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