Book vs Holy Writ

Book and Holy Writ both are nouns.

Word	Noun	Adjective	Verb	Adverb
Book	Yes	No	No	No
Holy Writ	Yes	No	No	No

As nouns, Book and Holy Writ are synonyms defined as:

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

Book (noun)	Holy Writ (noun)
the sacred writings of the Christian religions	the sacred writings of the Christian religions
the sacred writings of Islam revealed by God to the prophet Muhammad during his life at Mecca and Medina