dogmatic
dɒɡˈmatɪk
adjective
inclined to lay down principles as undeniably true.
she was not tempted to be dogmatic about what she believed
opinionated,peremptory,assertive,imperative,insistent,emphatic,adamant,doctrinaire,authoritarian,authoritative,domineering,imperious,high-handed,pontifical,arrogant,overbearing,dictatorial,uncompromising,unyielding,unbending,inflexible,rigid,entrenched,unquestionable,unchallengeable,intolerant,narrow-minded,small-minded