When we think of the brethren it is thought to be of one’s own family bloodline like brother, sister, or cousin yet to the Lord His Brethren are a family formed through His shed blood and receiving of the Holy Spirit. (Matthew 12:46-50). While he yet talked to the people, behold, his mother and his brethren stood without, desiring to speak with him. Then one said unto him, Behold, thy mother and thy brethren stand without, desiring to speak with thee. But he answered and said unto him that told him, Who is my mother? and who are my brethren? And he stretched forth his hand toward his disciples, and said, Behold my mother and my brethren! For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother.
Brethren are those who are like minded for the same cause, a kindred Spirit like how we meet a good friend who loves the Lord as well, and as Christ sanctifies we are all considered to be Brethren. (Hebrews 2:9-13). But we see Jesus, who was made a little lower than the angels for the suffering of death, crowned with glory and honour; that he by the grace of God should taste death for every man. For it became him, for whom are all things, and by whom are all things, in bringing many sons unto glory, to make the captain of their salvation perfect through sufferings. For both he that sanctifieth and they who are sanctified are all of one: for which cause he is not ashamed to call them brethren, Saying, I will declare thy name unto my brethren, in the midst of the church will I sing praise unto thee. And again, I will put my trust in him. And again, Behold I and the children which God hath given me.
Christ was the first to conquer death and the grave, and as we have the promise of eternal life in Him we are known as the children of God with the firstfruits of the Spirit. We are predestined to be conformed to His image as Christ is the firstborn of many Brethren! (Romans 8:21-23,29,30). Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God. For we know that the whole creation groaneth and travaileth in pain together until now. And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body. For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren. Moreover whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.