"In 2010 the Pew Research Center calculated a total of sixty-seven million (PDF) Christians in China, approximately 5 percent of the country’s population. Other independent estimates suggest somewhere between 100 and 130 million. Purdue’s Yang projects that if "modest" growth rates are sustained, China could have as many as 160 million Christians by 2025 and 247 million by 2032. Much of the discrepancy between official government numbers in China and expert estimates can be attributed to Beijing’s nonrecognition of Christians engaged in religious activity outside of state-sanctioned religious organizations. A number of social scientists agree that surveys of China’s general population underestimate (PDF) the size of the Christian population because some respondents are not willing to admit Christian identity. But the Pew Research Center cautions this makes make it extremely difficult to measure accurate change over time and to identify patterns and make projections about switching into and out of Christian identity."
Stark and Wang estimate that in 1980 there were 10 million Christians in the People's Republic of China, and that in 2007 the figure was 60 million. These numbers yield an annual growth rate of 7 percent – which means that last year, there were nearly 100 million Christians in China."
In light of this new openness to Christianity across China as a whole, Stark supposed a continued 7 percent annual rate of growth of the religion. At that rate, there will be 150 million Christians in China in 2020; 295 million in 2030; and 579 million in 2040.
“The growth might stop: you never know what's going to happen in the future,” Stark said. “But at the current rate, there'll be a whole heck of a lot of Christians in China awfully soon.”