It's not just a Christian thing. It's more to do with the fact that the Chinese government see religion as a supernatural thing which flies in the face of communist ideology and is thus forbidden in movies destined for the Chinese market. And since China is a huge market these days, we see US film studios bending the knee to Chinese censorship in order to get a slice of the pie. And its not just movies either - we're seeing it in the video games market too, particularly on consoles and mobile platforms
I don't much care what another country does within the confines of its own borders, but when you see American companies pandering to authoritarian regimes like this, it leaves an unpleasant taste in the mouth
The world expects America to lead by example, not to kowtow to unpleasant ideologies just to make a fast buck