I have many contacts in Communist China, including two daughters-in-law who are Chinese with relatives still back in China. Before the bamboo curtain went up there was estimated to be about 2 million Christians in China, but the Communist went through sending all the Christian Chinese leadership for reeducation, all churches were closed and foreign missionaries were kicked out. The Communists liked the moral, ethical, obedience, servitude message of the Bible, so they eventually had 90 million printed up and sold for just a fraction of the cost at registered Christian Churches but did not allow any other Christian religious books (except, they did allow the Catholic Catechism book, but few sold). Up until a few years ago they could buy Bibles online, but not commentaries.
Prior to the bamboo curtain coming down it was though Christianity was dead in China, but instead it had grown to an estimated 75 million unregistered Christians and thought to be as large as 175 million meeting in homes each Sunday these days, yet there is strong persecution.
I know, what some Chinese Christians teach from different places in China and it is a miracle to realize, they are all teaching the same doctrine without any cross communication, religious books other than the Bible, but we can thank to the Communist Government for that. The Communist made public a long list of what could not be taught in the registered Christian Churches which included: Christ is the son of God, Christ died for our sins, Christ rose from the dead, adult believer emersion water baptism, and so on. Since these unregistered Churches could not keep from breaking the law, they broke all the law, teaching all the doctrine not allowed and that makes them all alike.