Mt 12:48 But he answered and said unto him that told him, Who is my mother? and who are my brethren?
49 And he stretched forth his hand toward his disciples, and said, Behold my mother and my brethren!
50 For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother.
Those who love Him keep His commandments. Those who don't love Him, don't.
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Mt 10:34 Think not that I am come to send peace on earth: I came not to send peace, but a sword.
Lu 12:51 Suppose ye that I am come to give peace on earth? I tell you, Nay; but rather division:
No one is a brother or sister if they do not accept Him as the Saviour, the Messiah, Jesus the Christ .. That I take it is what you meant , right ?