Heretical as an adjective is (of ideas or views) contrary to mainstream or accepted opinion; (esp. views contrary to established teachings of the roman catholic church) but also contrary to other denominations while Heterodox as an adjective is of or pertaining to creeds, beliefs, or teachings, especially religious ones, that are different from the norm ('orthodox'), but not sufficiently different to be called heretical.
Part of speech: adjective
Definition: (of ideas or views) contrary to mainstream or accepted opinion; (esp. views contrary to established teachings of the Roman Catholic church) but also contrary to other denominations
Part of speech: adjective
Definition: Of or pertaining to creeds, beliefs, or teachings, especially religious ones, that are different from the norm ('orthodox'), but not sufficiently different to be called heretical.
We hope you now know whether to use Heretical or Heterodox in your sentence.