Not just Christians, they're persecuted Tibetan Buddhists and people who practice Falun Gong (Tai Chi and meditation).
This was the reason they gave for persecuting Falun Gong practitioners:
"The so-called 'truth, kindness and forbearance' principle preached by [Falun Gong] has nothing in common with the socialist ethical and cultural progress we are striving to achieve", and argued that it was necessary to crush Falun Gong to preserve the "vanguard role and purity" of the Communist Party.
https://en.wikipedia.org/wiki/Falun_Gong