diabolism vs necromancy

diabolism and necromancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
diabolism	Yes	No	No	No
necromancy	Yes	No	No	No

As nouns, necromancy is a hypernym of diabolism; that is, necromancy is a word with a broader meaning than diabolism:

diabolism: a belief in and reverence for devils (especially Satan)
necromancy: the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world

Other hypernyms of diabolism include black art, black magic, sorcery.

diabolism (noun)	necromancy (noun)
a belief in and reverence for devils (especially Satan)	conjuring up the dead, especially for prophesying
	the belief in magical spells that harness occult forces or evil spirits to produce unnatural effects in the world