This is the 5947th most frequent Chinese word.
天主教
Roman Catholicism.
Here, '天主教' is used as a noun to reference the religion of Catholicism, specifying its historical presence.
天主教在中国有悠久的历史。
Catholicism has a long history in China.
In this sentence, '天主教' modifies '教堂', specifying that the church belongs to the Catholic faith.
我今天去了天主教的教堂参加弥撒。
I went to the Catholic church today to attend Mass.
This usage of '天主教' specifies the theme of the study, which is related to Catholic rituals.