Actually, I would tend to disagree with that statement. That would certainly be true in America but here, I think that most Chinese people who go to church (whether house or government) on Christmas Day probably are Christians (or at least profess to be). It’s not like in the U.S. where EVERYBODY goes to church or ‘mass’ on major holidays.
In the US everyone doesn’t go for Church mass on major holidays — or “services” at their local — there are quite a few Jews, Hindus, Muslims, Mormons etc. as well as atheists.