truth vs gospel truth

truth and gospel truth both are nouns.

Word	Noun	Adjective	Verb	Adverb
truth	Yes	No	No	No
gospel truth	Yes	No	No	No

As nouns, gospel truth is a hyponym of truth; that is, gospel truth is a word with a more specific, narrower meaning than truth:

Other hyponyms of truth include gospel, tautology, truism.

truth (noun)	gospel truth (noun)
the quality of being near to the true value	an unquestionable truth
a fact that has been verified
a true statement
conformity to reality or actuality