mantra vs religious writing

mantra and religious writing both are nouns.

Word	Noun	Adjective	Verb	Adverb
mantra	Yes	No	No	No
religious writing	Yes	No	No	No

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

mantra: (Sanskrit) literally a `sacred utterance' in Vedism; one of a collection of orally transmitted poetic hymns
religious writing: writing that is venerated for the worship of a deity

Other hypernyms of mantra include religious text, sacred text, sacred writing.

mantra (noun)	religious writing (noun)
(Sanskrit) literally a `sacred utterance' in Vedism; one of a collection of orally transmitted poetic hymns	writing that is venerated for the worship of a deity
a commonly repeated word or phrase