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believer; adherent; devotee; follower
fanboy; fanatic; superfan
彼はその宗教の熱心な信者として知られている。
He is known as a devout follower of that religion.
新興宗教の信者が急速に増加している。
Followers of new religions are rapidly increasing.
教祖の言葉に信者たちは深く感銘を受けた。
The followers were deeply moved by the founder's words.