N-PLURAL [oft with poss](某组织或团体的)成员,会员;(尤指宗教团体的)教友 You can refer to the members of a particular organization or group, especially a religious group, as brethren. (某组织或团体的)成员,会员;(尤指宗教团体的)教友 [old-fashioned]
We must help our brethren, it is our duty.
我们必须帮助我们的教友,这是我们的责任。
Sri Lankans share a common ancestry with their Indian brethren.