heathenism vs religious belief

heathenism and religious belief both are nouns.

Word	Noun	Adjective	Verb	Adverb
heathenism	Yes	No	No	No
religious belief	Yes	No	No	No

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

heathenism: any of various religions other than Christianity or Judaism or Islamism
religious belief: a strong belief in a supernatural power or powers that control human destiny

Other hypernyms of heathenism include faith, religion.

heathenism (noun)	religious belief (noun)
any of various religions other than Christianity or Judaism or Islamism	a strong belief in a supernatural power or powers that control human destiny