'Brethren' in the Bible

If thou put the brethren in remembrance of these things, thou shalt be a good minister of Jesus Christ, nourished up in the words of faith and of good doctrine, whereunto thou hast attained.

Rebuke not an elder, but intreat him as a father; and the younger men as brethren;

And they that have believing masters, let them not despise them, because they are brethren; but rather do them service, because they are faithful and beloved, partakers of the benefit. These things teach and exhort.