heretic + -al

believing in or practicing religious heresy:

(宗教上)異端［論］の

e.g. heretical beliefs

e.g. a heretical theologian.

holding an opinion at odds with what is generally accepted:

(一般に)異端［論］の

e.g. I feel a bit heretical saying this, but I think the film has too much action.

heretically adverb