That's because the Bible simply calls the Church founded by Christ as "The CHURCH". In grammar, the article "the" followed by a noun is definitive.
Here is what the dictionary explanation:
The definite article the is the most frequent word in English.
We use the definite article in front of a noun when we believe the hearer/reader knows exactly what we are referring to.
• because there is only one:
The Pope is visiting Russia.
The moon is very bright tonight.
The Shah of Iran was deposed in 1979.
This is why we use the definite article with a superlative adjective:
He is the tallest boy in the class.
It is the oldest building in the town.
• because there is only one in that place or in those surroundings:
Therefore from the mouth of the enemies of The CHURCH, we proclaim the truthfulness of THE CHURCH known througout the whole world as THE ONE, HOLY, CATHOLIC and APOSTOLIC CHURCH of CHRIST!