Adherent means someone who follows or supports a leader, cause, idea, etc.
Adherent is a noun.
Synonyms: fan, follower, advocate, supporter, disciple, patron, backer, champion, devotee.
Antonyms: adversary, detractor, opponent.
The new religious political leader already has adherents; he has thousands of devoted followers.
We expect strict adherence to factory rules.
We cannot expect to have a peaceful society without strict adherence to the laws.