Developing young people's "religious literacy" would help to make them less vulnerable to radicalisation, a conference will hear later.
"Good religious education has never been more needed," Ed Pawson, chairman of the National Association of Teachers of Religious Education, will say.
But pupils will miss out unless the government addresses a shortage of RE teachers, he will warn.
The government said training bursaries would help to recruit more RE staff.
'Never more threatened'
In a speech to NATRE's inaugural annual conference, Mr Pawson is expected to ask "what hope" there is for students to receive a strong religious education when so few of those teaching the subject are qualified to do so.
RE "has never been under greater threat", he is expected to say.
Mr Pawson will cite official figures that show 54% of secondary RE teachers have no post-A-level qualification in a related subject.
"This compares very unfavourably with history, where a mere 27% of teachers lack post-A-level expertise."
Primary pupils are even worse served, he will add, with a NATRE survey of teachers in 2013 suggesting half of almost 700 who responded had received only three hours' training in the subject. A quarter had no training at all.
"We must work hard to attract bright young graduates to join the RE profession, bringing with them energy, creativity and a vision for a more respectful, understanding and diverse society - but let's be honest about some of the facts: as a subject, we need more resources."
Mr Pawson is expected to mention Ofsted's 2013 report on RE, which said more than half of schools were failing pupils on religious education and raised "significant concerns" about the training deficit.
This report found low standards, weak teaching, a confused sense of the purpose of religious education, training gaps and weaknesses in the way the subject was examined.
A report by MPs from the same year said many primary subject leaders in RE lacked sufficient experience and expertise to fulfil the role.
On top of this, from 2016, proposed changes to GCSE subject specifications for RE, requiring the study of two religions, will pose even greater challenges to teachers, he will argue.
"There is still a mountain to climb to bring RE teachers up to the level of qualification and skill that is required to make it a vibrant, exciting and academically rigorous subject in all our schools."
In the speech, Mr Pawson is expected to describe England's Education Secretary Nicky Morgan as "supportive" of religious education.
He promises NATRE will be "candid about the significant obstacles we face" in forthcoming meetings with ministers.
The government said RE was a "vital part" of its plan to prepare young people for life in modern Britain by helping children to develop an understanding of the different faiths and cultures which make up our society.
"That is why it remains compulsory at all key stages, including at primary," a Department for Education spokesman said.
From September top graduates, "including those with the potential to be exceptional RE teachers", could apply for a training bursary "worth £9,000 for a first-class degree and £4,000 for a 2:1", he added.