British Prime Minister David Cameron stands at a lectern during a March 3 memorial service for the late former South African prime minister Nelson Mandela at Westminster Abbey in London. (John Stillwell/ AFP/Getty Images)

"I believe we should be more confident about our status as a Christian country," British Prime Minister David Cameron wrote last week, "more ambitious about expanding the role of faith-based organisations, and, frankly, more evangelical about a faith that compels us to get out there and make a difference to people's lives."

Cameron's comments, written for the Church Times magazine, are not technically wrong. Britain has been a Christian-majority nation for more than a millennium, and the official religion in the country is the Anglican Church (Church of England), which is ceremonially led by Queen Elizabeth II.

But Cameron's article has been controversial. On Monday, a letter signed by more than 50 public figures that accused the prime minister of fostering "division" was published in the Daily Telegraph. "At a social level, Britain has been shaped for the better by many pre-Christian, non-Christian, and post-Christian forces," the letter's authors wrote. "We are a plural society with citizens with a range of perspectives, and we are a largely non-religious society."

That Cameron's comments can be true yet still controversial reflects the changing way British people have been thinking about religion in recent years. The chart below shows the current religious make up of the United Kingdom, according to the 2011 census:

As you can see, Christianity clearly dominates, though it's not near the 73 percent that you find in the United States. But it's not like other religions fill up that gap. Less than 8 percent of respondents gave a non-Christianity religion. Instead, more 30 percent of Britons either refused to list their religion, or said that they have no religion.

Other surveys tell an even more dramatic story: The 2013 British Social Attitudes Survey (BSA) found that 48 percent said they did not belong to a religion, whereas 68 percent said they were religious when the poll started in 1983. A 2011 YouGov poll found that only 34 percent of those asked would say they believed in "a God or gods," and 50 percent said they never went to place of worships outside of family events such as weddings and funerals. That last figure is important. While the British might be unenthusiastic about religion, it remains tied to British culture: The number of couples getting married at a church has actually grown in recent years, despite fewer people actually getting married.

There's also another factor at work here. For decades British policy has been led by a concept of multiculturalism: The idea that immigrant communities shouldn't be forced to assimilate, but that different cultures should be celebrated and encouraged. Over the past few years, multiculturalism has been criticized for being too vague or leading to moral relativism (Cameron himself argued that "state multiculturalism" had failed in Britain.) but it still holds sway with a large amount of British people.

The increasingly nonreligious make up of Britons and the belief in multiculturalism are difficult to square with Britain being a Christian country: Cameron might be technically right but practically wrong about the issue.

Its this confusion that has led other recent British leaders have avoided the question of religion altogether. Tony Blair (who converted to Catholicism after leaving office) was famously cut off by one of his most influential advisers when asked about his religion − "We don't do God," his PR expert Alaistair Campbell told him.

Cameron seems to be following a different tack, whether its sincere or not.