This week radio advertisements, devised by the Churches' Advertising Network (CAN), will start playing all over the UK on commercial radio stations, delivering the Christmas story in an unusual way.

Why? What does CAN hope to achieve from this?

The first question is simple. A Theos survey last year showed that only 12% of the population, and only 7% of young adults, had a reasonably comprehensive understanding of the Nativity.

There are undoubtedly many reasons for this but one is that there is increasing pressure, from a small if vocal quarter, to “secularize” the public square. Some businesses, for example, are increasingly nervous about sending Christmas cards and some schools about staging Nativity plays, for fear that it will supposedly cause offence to other faiths (or atheists).

The cumulative effect of this is an erosion of the knowledge of the basic tenets of Christianity, in what is supposed to be, at least notionally, a Christian country, a trend that is most pronounced among the increasing number of families with no direct contact with a church.

This campaign is an attempt to reach some of those young people outside the Church, to interest them in finding out more, using humour and an unexpected approach to engage their attention.

The bigger question is “will it work?” (and accordingly, “how will you know?”)

The truth is that there is a lack of consistent, quality research in this area, and funding shortages mean that those financial resources that are available are ploughed into the campaigns.

What we do know is that on its own, advertising is a relatively weak force. Whatever the product or service advertised, it needs to be part of a bigger outreach programme (one reason this year’s ads include a competition for people to create their own 30 second version of the Nativity story).

Ideally, the advertising should be a catalyst for a consistent, well-resourced programme of initiatives to keep retelling the Christmas story in this and future generations.

To be fair, the people who have had most difficulty with this in the past are Christians themselves. Gradually, however, some of this internal resistance to the concept of advertising the Christian faith is fading away, and a new generation of Church leaders is beginning to see that advertising can play a (not the) role in communicating the Christian message. The range of interesting new initiatives – from Alpha to Back-to-Church Sunday – is testimony to this.

If Christians can get this – seeing such campaigns not as an opportunity to “sell” the gospel or “convert” unbelievers – advertising could be very successful.

Christians recognise that they have a duty to show Christ’s relevance in the 21st century, a duty that extends well beyond the doors of their churches and right into the heart of our communities.

Advertising Christianity must fit into this wider picture. If it does, the sky is the limit.

Francis Goodwin is Chairman and founder member of the Churches Adverstising Network, and former Managing Director of The Maiden Group plc.