n
1 person who believes, esp sb with religious faith 笃信者; （尤指）教徒.
2 (idm 习语) be a (great/firm) believer in sth feel sure of the worth of sth 肯定某事物的价值
*I'm not a great believer in (taking) regular physical exercise. 我对经常锻炼身体的好处有点怀疑.

n[C]
be a (great/firm) believer in sth
to believe strongly that something is good and effective
　I'm a great believer in regular exercise.
someone who believes in a particular god, religion, or system of beliefs