Researchers describe a large proportion of the country as the “fuzzy faithful” who have a vague belief in God but do not necessarily belong to a particular denomination or attend services.
However, most people still say religion helps bring happiness and comfort, and regret its declining influence on modern society.
Professor David Voas, who has analysed the latest data, said: “More and more people are ceasing to identify with a religion at all.
“Indeed, the key distinction in Britain now is between religious involvement and indifference. We are thus concerned about differences in religiosity – the degree of religious commitment – at least as much as diversity of religious identity.”