diabolic vs unholy

diabolic and unholy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
diabolic	No	Yes	No	No
unholy	No	Yes	No	No

As adjectives, diabolic and unholy are synonyms defined as:

diabolic and unholy: extremely evil or cruel; expressive of cruelty or befitting hell

Other synonyms of diabolic include demonic, diabolical, fiendish, hellish, infernal, satanic.

diabolic (adjective)	unholy (adjective)
extremely evil or cruel; expressive of cruelty or befitting hell	not hallowed or consecrated
showing the cunning or ingenuity or wickedness typical of a devil	extremely evil or cruel; expressive of cruelty or befitting hell
	having committed unrighteous acts