Matthew 12:46-50, Mark 3:31-35, Luke 8:19-21

As the Savior was teaching his disciples -

"...his mother and his brethren stood without, desiring to speak with him." (New Testament Matthew 12:46)

And with traditional respect -

"...one said unto him, Behold, thy mother and thy brethren stand without, desiring to speak with thee." (New Testament Matthew 12:47)

To which the Savior answered in greater perspective -

"...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!" (New Testament Matthew 12:48 - 49)

Then he teaches -

"For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother." (New Testament Matthew 12:50)

Luke records that he also said -

"...My mother and my brethren are these which hear the word of God, and do it." (New Testament Luke 8:21)

"Hear the word of God , and do it" suggests that obedience is a key to the eternal family of Christ. King Benjamin taught -

"...because of the covenant which ye have made ye shall be called the children of Christ, his sons, and his daughters; for behold, this day he hath spiritually begotten you; for ye say that your hearts are changed through faith on his name; therefore, ye are born of him and have become his sons and his daughters." (Book of Mormon Mosiah 5:7)

For -

"...I am Jesus Christ. I am the Father and the Son. In me shall all mankind have life, and that eternally, even they who shall believe on my name; and they shall become my sons and my daughters." (Book of Mormon Ether 3:14)

As his family, we covenant that we -

"..are willing to take upon [us]the name of thy Son, and always remember him, and keep his commandments which he hath given [us]..." (Book of Mormon Moroni 4:3)

As we "hear the word of God, and do it" with other fellow saints, we develop a kinship as brothers and sisters in the family of Christ. Elder Bruce R. McConkie explained -

“This [the idea that we may become members of the family of Christ] is a special family relationship reserved for the faithful. It is over, above, and in addition to the fact that all men are the spirit children of the Eternal Father. . . . This is a glorious and wondrous doctrine. We are the sons and daughters of the living God, the children of the great Jehovah, the adopted offspring of the Lord Jesus Christ. We bear the name of Christ. We are members of his family. He is our father.” (McConkie, “The Ten Commandments of a Peculiar People,” Speeches of the Year, 1975, p. 30.)