Persistent religious belief

The number of serious Christians in China is estimated to be between 20 and 90 million.  Sorry for the imprecision in the number but that sort of thing in a country like China is hard to measure.  The actual number is probably on the higher side of this range (remember that China is a seriously big country).

These are mostly people in rural areas that have been Christian for generations and their descendants now moving to cities as part of China's overall planned urbanization, where they become more visible.  How have they persisted in spite of official condemnation and all sorts of discriminations?  The answer is easy: they indoctrinate their children, and no government in the world can defeat that short of breaking up families.

What you were taught as a child by your parents is almost certainly what you will believe, especially if it is done lovingly without brute force and consistently and with the parents setting a non-hypocritical example.  Those who do flirt with other belief systems in the vast majority of cases become lost sheep who experience the joy and peace of returning to the flock a decade or so later, all the time they experienced fear and guilt.

Those who don't return to the flock tend to develop hate for whatever they were indoctrinated into, and serious resentment over what was "done to them" as a child and the suffering this put them through until they were finally able to make a clean break. 

Thus religions and superstitions persist in spite of modern knowledge and rational thought.  It has to do with the way human beings are wired.