If you say that someone is doctrinaire or has a doctrinaire attitude, you disapprove of them because they have fixed principles which they try to force on other people.
[formal, disapproval]
He is firm but not doctrinaire.
More Synonyms of doctrinaire
doctrinaire in British English
(ˌdɒktrɪˈnɛə)
adjective
1.
stubbornly insistent on the observation of the niceties of a theory, esp without regard to practicality, suitability, etc
2.
theoretical; impractical
noun
3.
a person who stubbornly attempts to apply a theory without regard to practical difficulties
Derived forms
doctrinairism (ˌdoctriˈnairism) or doctrinarism (ˌdoctriˈnarism)
noun
doctrinarian (ˌdoctriˈnarian)
noun
doctrinaire in American English
(ˌdɑktrɪˈnɛr)
noun
1.
a person who dogmatically seeks to apply theories regardless of the practical problems involved