According to the British Academy, the number of undergraduates on those types of courses slumped by around a third between 2011 and 2017.
President Sir David Cannadine described the situation as a worrying trend.
He was quoted by the Sunday Times as saying: "Never has an understanding of our spirituality and the role of religion been more important to navigating the challenges we face."
Figures published by the exams regulator Ofqual last year revealed a 13 per cent drop between 2018 and 2017 in the number of youngsters studying GCSE Religious Studies.
The figure fell by 37,500 - from 297,800 in 2017 to 260,300 in 2018.
Religious studies was ranked among the secondary school subjects people in the UK considered least important, according to a YouGov poll published last year. Only twelve per cent thought the subject was "very important".
Commenting on a report by the British Academy, professor of church history Sir Diarmaid MacCulloch expressed concern at the dwindling number of students embarking on religion programmes.
He told the Sunday Times: "We have a multi-faith country which needs a first-class understanding of its religious profile to make it work properly."
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