A fifth of American adults and a third of those under 30 have no religious affiliation, according to the latest survey from the Pew Forum.

Of the 46 million Americans whose affiliation is described as "none", two-thirds say they believe in God and one-fifth say they pray daily. Some 88 per cent of these "nones" say they are not looking for a religion, and many said religious organisations are too concerned with money, power, rules and politics.

The percentage of Christians has fallen approximately one percentage point a year since 2007 to 73 per cent, with Protestants showing a similar decline in numbers and now standing at less than half - 48 per cent - and Catholics holding steady at around 22 per cent, partly due to immigration from Latin America.