A person who believes in, practices, or emphasizes doctrines and strict adherence to established principles and teachings.
From doctrinal + -ist (from Greek -istēs 'one who practices'). The -ist suffix identifies someone committed to a particular practice, belief, or system.
Whether calling someone a 'doctrinalist' is an insult or compliment tells you a lot about the speaker: idealists see principled consistency, while pragmatists see dogmatic inflexibility.
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