Despite the rise of secularism, 37.3 million described their religion as Christianity, according to the 2001 Census, the Telegraph newspaper reported.
The census, the first to ask a question on religion, confirmed Islam as the second largest faith, with 1.54 million (3.1%).
Other tallies include 552,000 Hindus (1.1%), 329,000 Sikhs (0.6%), 260,000 and Jews (0.5%). About 7.7 million (14.8%) said they had no religion.
The census also revealed that more than a quarter of the population in Scotland, 28%, now say they have no faith, the Scotsman newspaper noted.
The biggest religion there is still the Church of Scotland, with 42.4% of the population, but the census indicated a drop-off rate of just under 5%, with 47% saying they were brought up in the faith.
The Catholic Church has also seen a decline in numbers, with some 16% saying they were still practicing, compared with 17% who were brought up in the faith.
