Christians have been persecuted by polytheists, atheists, Muslims, and many others. Ancient Rome sent many Christians to the lions. The USSR had official state atheism, for example, and persecuted Christians. Certainly Christians have persecuted other Christians, but I think there's little evidence that Christians have been the dominant ones. Much more info is here: https://en.wikipedia.org/wiki/Persecution_of_Christians
On the other hand, clearly many atheists allow others to have different beliefs, including Christian beliefs, and to allow religious texts to be distributed (such as the Bible).
This seems to be much more about power and control over the Chinese people.