Because that’s the definition I’m working with. The other definition is legitimate but not as universal. Most words have multiple definitions. I’m under no obligation to choose the definition that you prefer.
There is NO DEFINITION of the Catholic Church (capitalized as proper nouns) which refers to anything other than the Catholic Church of which His Holiness Benedict XVI is the pope, nor is there a definition of Catholic as a proper noun which refers to anyone other than a member of the Catholic Church.
Most words have multiple definitions. I’m under no obligation to choose the definition that you prefer.
No you aren't but when you begin to use a word as a proper noun, the applicable definitions become limited.
You rather deceptively imply a single definition for a word that, by your source, has two.