Clement is known for his part in the Chinese Rites controversy. Catholic missionaries in China were debating whether or not local practice of making offerings and burning incense to ancestors and Confucius were idolatrous. Most of the local missionaries leaned toward the liberal idea: these practices were not really religious in nature, but more likely social conventions that helped hold society together. (Perhaps we can compare this to Santa Claus at Christmas. He's not an object of religious worship, but we still sing songs about him, have elaborate rituals about his arrival, and even leave food offerings out for him.)

Clement, who never earned that name, came down on the side of idolatry. He demanded that Chinese Christians stop these practices, and even went so far as to command that they use the latin "Deus" to refer to God, instead of the more Chinese-friendly "Shangdi", or Heavenly Lord. Not surprisingly, this pissed off the emperor - he banned Catholic missionaries.