Good Book vs religious writing

Good Book and religious writing both are nouns.

Word	Noun	Adjective	Verb	Adverb
Good Book	Yes	No	No	No
religious writing	Yes	No	No	No

As nouns, religious writing is a hypernym of Good Book; that is, religious writing is a word with a broader meaning than Good Book:

Other hypernyms of Good Book include religious text, sacred text, sacred writing.

Good Book (noun)	religious writing (noun)
the sacred writings of the Christian religions	writing that is venerated for the worship of a deity