The Bishop of Manchester will today launch a church-backed advertising campaign promoting the message that Christmas starts with Christ.

A huge poster measuring 40 feet high and the length of three buses will be fixed to scaffolding on the side of St Ann's church at the heart of Manchester's shopping and commercial district.

It will read: 'Does Christmas have to start with a payday loan? No! Christmas starts with Christ.'

The poster will be the UK's biggest outdoor religious Christmas ad, and is expected to be seen by millions.

It is part of the Christ Starts with Christmas campaign reminding people of the real meaning of Christmas, and has been sponsored by the Diocese of Manchester in partnership with the Church of England, ChurchAds.net, St Ann's Church and Churches Together in Greater Manchester.

Bishop David Walker spoke of the importance of remembering the true reason we celebrate Christmas in an increasingly secular society.

"We are asking people to pause and to remember that Christmas does not start with high interest loans or Christmas specials on TV. Christmas Starts with Christ," he said.

Christmas has become increasingly commercialised in recent years, and in light of shocking statistics that reveal the extent to which its true meaning has been lost, Francis Goodwin, a key figure behind the Christmas Starts with Christ campaign, warns that "a tipping point has been reached".

"Christmas is being lost to secularism and the trend is for this to get worse," he said.

"Just 12 percent of adults know the nativity story; and 36 percent of children do not know whose birthday is being celebrated during the festival.

"Fifty-one per cent of people now say the birth of Jesus is irrelevant to their Christmas."

Reverend Nigel Ashworth, the Rector of St Ann's in Manchester, has said that the church is delighted to be able to display the Christmas message "so visibly at the heart of this great city".

General Director of the Evangelical Alliance, Steve Clifford, has also praised the campaign, saying that it "seeks to show that the Church is good news for the nation in every season, not least of all at Christmas when we celebrate the birth of Jesus Christ, our Saviour".

"The world needs to know that's why we do what we do."

Hundreds of other sites around the country will also display the posters. It is hoped that they will inspire people to check out their local church and find out more about the Christian faith.