More people in England and Wales say they have no religion than say they are Christians, according to new analysis – and the number is increasing.
Stephen Bullivant, senior lecturer in theology and ethics at St Mary's Catholic University in Twickenham, analysed data collected through British Social Attitudes surveys over three decades.
He found that the number of people saying they had no religion – or 'nones' – was 48.5 per cent in 2014, almost double the figure of 25 per cent in 2011. Christians made up 43.5 per cent of the population.
"The striking thing is the clear sense of the growth of 'no religion' as a proportion of the population," Bullivant said.
"The main driver is people who were brought up with some religion now saying they have no religion. What we're seeing is an acceleration in the numbers of people not only not practising their faith on a regular basis, but not even ticking the box. The reason for that is the big question in the sociology of religion."
The report did not examine data from Scotland or Northern Ireland but a Scottish Social Attitudes survey last month found a similar trend, with 52 per cent of the population saying they were not religious compared with 40 per cent in 1999. Northern Ireland presents a radically different picture, with only seven per cent in the 2011 census saying they were not religious or belonged to a non-Christian religion.
The report says both Catholics and Anglicans are struggling to retain people brought up in the faith. Four out 10 adults raised as Anglicans now say they have no religion, and almost as many "cradle Catholics". Neither Church is making up for its losses through conversions; Anglicans lose 12 worshippers for every convert and Catholics 10. And, said Bullivant, most converts come from other Christian denominations, rather than non-Christians or people with no religion. "There's a kind of denominational musical chairs," he told the Guardian. "No one is making serious inroads into the non-Christian population."
A spokesperson for the Church of England said: "The increase in those identifying as 'no faith' reflects a growing plurality in society rather than any increase in secularism or humanism. We do not have an increasingly secular society as much as a more agnostic one.
"In a global context, adherence to religion is growing rather than decreasing. Christianity remains the world's largest religion with over 2 billion adherents. In the UK the latest census found the overwhelming majority of people to have a faith."
The report will be launched in the House of Commons today.