Why does the underground church of China continue to grow? How did it survive through the harshest years of communism?
"They did not depend on a centralized structure. Any believer could plant a church, preach, and baptise others. In this way they could multiply in secret. Also, strong organisations are easy to target. You can destroy their buildings, freeze their assets and arrest their leaders, but a church that does not depend on buildings, bank accounts or a hand-full of leaders, is very hard to control."

https://backtojerusalem.com/where-are-the-churches-in-china-and-why/