In China it is known as the “sacred doctrine” and it has become one of the country’s bestselling books. Yet it has nothing to do with the thoughts of Chairman Mao and its teachings have been in conflict with the forces of Communism for generations.

Demand for the Bible is soaring in China, at a time when meteoric economic growth is testing the country’s allegiance to Communist doctrine. Today the 50 millionth Bible will roll off the presses of China’s only authorised publisher, Amity Printing, amid public fanfare and celebration.

In the past, foreign visitors were discouraged from bringing Bibles into the country in case they received some heavy-handed treatment from zealous Customs officials.

Such is the demand in China for Bibles that Amity Printing can scarcely keep pace. Early next year it will move into a new, much larger factory on the edge of the eastern city of Nanjing to become the world’s single-biggest producer of Bibles.

One book a second glides off the production line at this joint venture between a Chinese Christian charity and the United Bible Societies, a Protestant organisation. Amity has been printing Bibles since 1986. The new factory will have a capacity of one million Bibles a month, increasing the current output by one third.

New Zealander Peter Dean, of the United Bible Societies, bustles between the humming state-of-the-art presses. Mr Dean, who has been in China at Amity since 1991, said: “This platform has been built as a blessing to the nation. It will print Bibles for China for as long as it takes to do it.” Authorities at the officially approved Protestant and Catholic churches put the size of China’s Christian population at about 30 million. But that does not include the tens of millions more who worship in private at underground churches loyal to the Vatican or to various Protestant churches.

Of the 50 million Bibles Amity has printed, 41 million were for the faithful in Chinese and eight minority languages. The rest have been for export to Russia and Africa. Sales surged from 505,000 in 1988 to a high of 6.5 million in 2005. Output last year was 3.5 million and is expected to rise in 2007.

One of Mr Dean’s bestsellers is a pocket Bible, a version not suitable for the older generation to read and which may indicate a rapid expansion in the number of new, younger believers. He cited a surge in demand during the Sars crisis in 2003, but refrained from commenting. The enterprise has clearly flourished through its discretion and careful adherence to China’s laws that prohibit evangelising.

The Bible is not on sale in mainstream Chinese bookshops but through a distribution system managed by the official church, for example at stalls set up for people attending morning service. But it does figure on a recommended reading list of useful books in the glitzy metropolis of Shanghai.

A country where the Communist ideology has lost much credibility is seeing an upsurge in conversions to Christianity. Li Baiguang, a prominent lawyer and Christian activist who was received by President Bush at the White House last year, said: “Rising wealth means that more and more people have been able to meet their material needs, the need for food and clothing.

“Then they are finding that they need to satisfy their spiritual needs, to look for happiness for the soul. In addition, they are seeing a breakdown in the moral order as money takes over. Thus, more and more people are turning to Christianity.”

In the ultra-leftist Cultural Revolution between 1966 and 1976, Bibles were burnt as tomes of superstition. Much has altered since the 1980s when government policy required tourists and visitors not to bring in Bibles “in excess of personal use”. Many faithful took to smuggling the book into China to meet demand.

Cases of Bible smuggling are still reported and some people have been deported and locals even jailed. The Bibles they are smuggling usually contain the accepted gospel and an additional chapter slipped in among the pages relating to a particular sect or cult trying to spread its own beliefs.

It is such a sensitive issue that Chinese officials denied rumours recently that China would ban international athletes from bringing in Bibles to the Olympics in Beijing next August. However, the official Olympic website states: “Each traveller is recommended to take no more than one Bible into China.”

With China’s economy set to boom, Amity expects even higher demand when its new factory opens.

Mr Dean gestures to a new paper-sorting machine destined for the printing plant that had to be installed in the old facility recently to cope with demand. He is unconcerned about possible excess capacity. “Our lamp is full and the wick trimmed,” he said.

The believers

31% of China’s 1.05 billion adults consider themselves religious

200m of them are Buddhists or Taoists

40m the estimated population of Christians in China

1-2% are Muslims

1949 year China became officially atheist

Sources: China Daily; Central Intelligence Agency