What the Chinese “Ceasers” don’t understand is that once Christ enters the cracks it will never go away.
The state churches (with their government sermons) are no match for the “fire of truth”.
St. Paul would be impressed with the underground churches and would admonish the the government churches.
I’ve seen estimates of the number of Christians from 80 million to 150 million, or more that 10% of the population.
I think this is how they want it. Nature abhors vacuum. Islamists and other cultists have fewer chances to convert a believer than an atheist or (more likely) someone who never gave religion a thought.
The requirement for state-approved priests probably comes from experience with religions like Falun Gong. Christianity is a safe, established belief which isn't going to change overnight. Chinese rulers know that a bishop is not likely to hack into a satellite or release sarin gas into a subway system, or to commit a "revolutionary suicide".