Sectarianism as a noun is rigid adherence to a particular sect, party or denomination. while Denominationalism as a noun is the division of one religion into separate groups, sects, schools of thought or denominations.
Part of speech: noun
Definition: Rigid adherence to a particular sect, party or denomination.
Part of speech: noun
Definition: The division of one religion into separate groups, sects, schools of thought or denominations.
We hope you now know whether to use Sectarianism or Denominationalism in your sentence.