We are halfway through the season of Advent, when Christians look forward to the return of Jesus Christ and also start celebrating Christmas, his first time on Earth. Unfortunately, according to the 2011 Census results just released, there are more than four million fewer Christians celebrating now than ten or so years ago.

It seems somewhat careless for the Church to lose so many believers and rather a setback – and does it mean that in politics we need pay less attention to faith.

The census asked the voluntary question, “What is your religion?”. In 2001, 71.7% replied they were Christian. In 2011, that figure had fallen to 59.3%. Meanwhile, those declaring themselves of no religion (not necessarily the same thing as being atheist) rose from 14.1% to 25.1%, as Chart 1 shows.

Chart 1:

The ONS notes that the 2011 Census data are similar to other surveys of religious belief: it quotes the 2011 Annual Population Survey which showed 63.1% of the population is Christian, 4.8% Muslim, and 27.9% have no religion.

Much depends on how you view the 2001 figures and so the difference in 2011. It was not the case that in 2001, 71.7% of people were regular churchgoers and neither in 2011 was 59.3% of the population. The data measure religious affiliation, not activism. What we might call active Christians, those who attend church, have always formed a smaller, but still significant, proportion of the population.

For example, in 2007, Tear Fund, a Christian international development charity, conducted a survey (of 7,000 people) which found 15% of adults attended church at least once a month, with 10% attending weekly (this would equate to almost 5 million), and 26% attended at least once a year, equivalent to 12.6 million (the survey found 53% of adults called themselves Christians).

Demos, in its Faithful Citizens report published this year, found 13% of people said they belonged to a church or religious organisation (which includes other faiths).

We have, in many ways, a secular society (and the higher proportion of those without religious affiliation needs to be recognised). Yet it is telling such high proportions of people see themselves as having an affinity with the Christian faith (and other faiths too). It is odd we are having so many tense debates about the role of faith in public life. They seem divorced from the reality which is that most of the country describes itself in some way as Christian.

While the number has fallen, it still far outshines the affiliation to any political party. To understand the UK, we need to understand faith and understand it is public as well as private. We can see it in evidence today; for example in the hard work churches and other faith groups put into strengthening society, especially through helping the poor and socially excluded.

Demos found those who belonged to a religious organisation were more likely than others “to volunteer for local community action, youth work, development and human rights issues, women’s issues and the environment”; they were also “more likely to have attended a lawful demonstration”.

To ignore this in politics is to ignore a vital characteristic of our own country and its citizens. Something about British society at its best means we can be confident in our Christian heritage in a way which upholds freedom of expression of all religious, or no religious, faith. The rise of those declaring themselves of no religion, and of those affiliating to a religion other than Christianity, demonstrates this.

The Church (in its various denominations) will continue to be concerned about people’s spiritual health, about whether or not they are right with God and have responded to the message of love and forgiveness. As for those of us in politics, we should not rush to discount or explain away the 59.3% who call themselves Christian.

The fact is, they do. Perhaps we should follow the lead given by Elizabeth I and resolve not to “open windows into men’s souls”. Politics that does not recognise religion – not just as some constituency to placate but as a part in some way of most people’s lives and of their identity – will be separate from and out of touch with the society it seeks to serve.

This article was first published by Left Foot Forward, on 14 December 2012.