According to the state newspaper, the proposal to make all buildings fly the flag came from “the country’s major religious associations.” China recognizes only five religions legally—Protestant Christianity, Catholic Christianity, Islam, Taoism, and Buddhism—and has established government-recognized “patriotic” institutions that govern each.
"Christians in China are being forced to adhere to revised regulations on religion that were implemented in February which has led to strict government controls on their everyday lives. . . . Some of the most notable restrictions prohibit parents from bringing their children to church, while religious venues are banned from holding training sessions." CPost
"Many believe that this is a move by the Chinese government to show the state and the world just how serious it is about its new rules regarding regulating religion in order to enhance national security, dismantling and preventing extremism, and curbing the practice of faith by organizations which are not approved by the state." WRNews
"According to China Aid . . . personnel of the religious affairs bureau and the police raided the Olive Tree Church's Sunday worship service on the morning of July 10. The officials took pictures of the congregation, confiscated church property, banned their church meetings, sealed the church doors and then took away 30 of its members to the police station." ChristianTimes