Christian Bible vs Good Book

Christian Bible and Good Book both are nouns.

Word	Noun	Adjective	Verb	Adverb
Christian Bible	Yes	No	No	No
Good Book	Yes	No	No	No

As nouns, Christian Bible and Good Book are synonyms defined as:

Christian Bible and Good Book: the sacred writings of the Christian religions

Other synonyms of Christian Bible include Bible, Book, Holy Scripture, Holy Writ, Scripture, Word, Word of God.

Christian Bible (noun)	Good Book (noun)
the sacred writings of the Christian religions	the sacred writings of the Christian religions