Is buddhism and christianity spreading like ''wildfire'' in china?

Christianity always spreads quickly whenever it is persecuted. It is a puzzle, but true. I think this is because it is forced to person-to-person intimate instruction. On this level, Christianity is easily taught and spread because individuals that understand it can easily teach someone through difficulties. If a person who does not understand it tries to teach it, nobody will "get" it and the persons teaching career will end quickly. If it is permitted officially, however, it becomes homogenized and taught almost as a kind of mythos, like the Easter Bunny or Santa Claus and the many problems people have are often unanswered. People will call themselves "Christian" openly, even though they really don't live by the teachings (as in the US). I think the stories I have read saying that there are currently over 100 million Chinese Christians are very believable. If you think about it, you can easily understand how this can happen. If Christianity really represents a truth, like say "Math", and it "works" then one person can teach 20 people easily within a few years. These 20 people will then teach 20 others, each, within a few years and those 20 people will teach 20 more. 20x20x20x20- in only one generation (since the 1980s for example) - you could have over 64 million followers, each personally dedicated to following the precepts and eagerly sharing with their friends and family what they have learned. If Christianity does indeed teach some kind of truth, then this can easily happen. If it is all ridiculous myth, it cannot happen- ever.