disbelief vs mental rejection

disbelief and mental rejection both are nouns.

Word	Noun	Adjective	Verb	Adverb
disbelief	Yes	No	No	No
mental rejection	Yes	No	No	No

As nouns, disbelief and mental rejection are synonyms defined as:

Other synonyms of disbelief include incredulity, scepticism, skepticism.

disbelief (noun)	mental rejection (noun)
doubt about the truth of something	doubt about the truth of something
a rejection of belief