Religion in the United States is in decline, according to new research from University College London (UCL) and Duke University in the US.

America has long been thought to be the exception to the rule that religion is in decline in the Western world because of its relatively high levels of churchgoing.

However, the study by David Voas and Mark Chavez published in the American Journal of Sociology shows a drop in the number of Americans who claim religious affiliations, attend church regularly and believe in God. Furthermore, it says younger people are increasingly irreligious: "...this decline has been produced by the generational patterns underlying religious decline elsewhere in the West: each successive cohort is less religious than the preceding one. America is not an exception."

The study examined US data from the General Social Survey, which is conducted every two years, and compared it with similarly broad data from Great Britain, Canada, Australia and New Zealand. The results show that people have slowly become less religious over time.

The study found 68 per cent of Americans aged 65 and over said they had no doubt God existed, compared to 45 per cent of young adults, aged 18-30. While 41 per cent of people 70 and older said they attend church services at least once a month, only 18 per cent of people 60 and below do so.

Prof Voas said: "These declines aren't happening fast, but the signs are now unmistakable. It has become clear that American religiosity has been declining for decades, and the decline is driven by the same dynamic of generational change that has driven religious decline across the developed world."

Prof Chavez said: "The US decline has been so gradual that until recently scientists haven't had enough data to be sure the trend was real. The US has long been considered an exception to the modern claim that religion is declining, but if you look at the trajectory, and the generational dynamic that is producing the trajectory, we may not be an exception after all."