My notes on some of the reasons for the growth of (Protestant = evangelical) Christianity in China given by Stark and Wang :
Persecution was the single most important factor in the growth of Christianity in China since 1949. By expelling Western missionaries the Communists completed the transformation of Protestantism in China into an entirely Chinese movement.
Some Western Protestant missionaries had begun to lose faith not only in missions but in Christianity. Their expulsion protected the Chinese church from the debilitating influence of theological liberalism. Luke-warm liberalism cannot generate high levels of commitment.
Persecution results in a high level of member intensity. High levels of commitment are required for rapid growth. Committed people share their faith with others.
Most conversions occur through networks of interpersonal relationships. Conversion is not a very visible phenomenon. To deprive a faith of a public presence has little impact on its growth if members are engaged privately in converting their friends and family.
During the Cultural Revolution (1966-76) most churches were destroyed or converted into other uses. Thousands of clergy were jailed or forced into re-education camps. The Catholics were vulnerable due to their hierarchical structure and dependence on ordained clergy and sacred buildings. Soon their was an acute shortage of priests. Without priests there were no Masses and no baptisms.
In contrast, Protestants had a seemingly inexhaustible supply of preachers, male and female. Any devoted believer can conduct a church gathering. Protestants are able to pray, read the Bible and worship in homes.
In 1950 the Catholics outnumbered Protestants by 3 to 1. Today Catholics are outnumbered by Protestants 10 to one and the ratio is increasing.