Dogmatic
Part of speech: adjective
Definition: Stubbornly adhering to insufficiently proven beliefs; inflexible, rigid.
Example sentence: I'm not a dogmatic, purist psychopath. There's an unfair image of me - mean, crazy, hostile. I'm really a very gentle person.
Doctrine
Part of speech: noun
Definition: A belief or tenet, especially about philosophical or theological matters.The body of teachings of a religion, or a religious leader, organization, group or text.
Example sentence: Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment.