One of the common criticisms of our church that I hear from non-lds, is that we believe that Jesus and Satan are actually spirit brothers. I want to address this criticism, and explain the doctrine behind this teaching. I think a study of the Bible will show that this teaching does have basis in the scriptures.
I think the best place to begin is with this scripture from Romans 8:16,17: "The Spirit itself beareth witness with our spirit, that we are the children of God: 17 And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together." It is no wonder that we call God our "Heavenly Father". Hebrews 12:9 says,
"Furthermore we have had fathers of our flesh which corrected us, and we gave them reverence: shall we not much rather be in subjection unto the Father of spirits, and live?" Another good scripture to show this teaching is found in Numbers 16:22: " And they fell upon their faces, and said, O God, the God of the spirits of all flesh, shall one man sin, and wilt thou be wroth with all the congregation?" Or how about this one from Psalms 82:6 " I have said, Ye are gods; and all of you are children of the most High." And this one from Acts 17:9 "Forasmuch then as we are the offspring of God, we ought not to think that the Godhead is like unto gold, or silver, or stone, graven by art and man’s device." He is the father of our spirits.
In the pre-existence, before this world was made, we lived with God. Consider this scripture from Jeremiah 1:4-5: "Then the word of the Lord came unto me, saying, 5 Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations." Jeremiah was with God before he was born, and was fore-ordained as a prophet. Not only Jeremiah was present then, but we all, as spirit children of God, were there. Among our numbers was Lucifer, who is known more commonly today as "the Devil".
God proposed the plan of salvation, whereby we all could be saved. This plan was dependent upon our having free agency to choose for ourselves. This life then became a test, to see if we would follow God or not. Lucifer proposed another plan, and suggested that instead of having free will, we should be forced to obey. He felt that in this way, we could all be saved. In addition, he sought after the glory that would come to him if his plan worked. He sought to exalt himself above God. One third of the spirit children of God chose to follow Lucifer's plan.
God's plan depended upon a Savior that would come to atone for the sins of the world, and would also overcome death and bring about the resurrection. Jesus offered to be the Savior for us all.
Of course Lucifer was very upset, and a war ensued. Lucifer and his followers were cast out of heaven; cast down to this earth. We have this account from the book of Revelation which speaks about Satan and his followers, and about the birth of Jesus Christ:
Revelation 12: 4-9: " 3 And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.
4 And his tail drew the third part of the stars of heaven, and did cast them to the earth: and the dragon stood before the woman which was ready to be delivered, for to devour her child as soon as it was born.
5 And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and to his throne.
6 And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days." (Remember when Joseph took Mary and Jesus in to Egypt to escape King Herod's plan to kill all of the young children?)
7" And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8 And prevailed not; neither was their place found any more in heaven.
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him."
Notice that in verse 9 it mentions that this act of rebellion, and the war that he waged, is what earned Lucifer the titles of Devil, and Satan.
In Isaiah we read more about this fall. Isaiah's description of this event is quite moving, and we can feel his sadness that Lucifer should fall from God's presence.
12 How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations!
13 For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north:
14 I will ascend above the heights of the clouds; I will be like the most High.
15 Yet thou shalt be brought down to hell, to the sides of the pit.
So we see that Lucifer, or the Devil, fell from a place of greatness. He had been called "son of the morning", but now was called the Devil. He was also a spirit child of God, but chose to rebel against God, thereby being cast out from the presence of God.
Many people that I have talked to have been upset that I would suggest that Jesus had any connection to the Devil. But let's consider for a moment the rest of our spirit brothers and sisters. If we are indeed children of God, then all of mankind are spirit brothers and sisters. That means that even Hitler, and pedophiles, and serial killers, and drug lords, and dictators are spirit children of God. They are part of this great family of humans. They are children of God. However, their choices separate them from God in the hereafter. If they do not rely on the atonement of Jesus Christ, and repent of their sins, they will not have a place with God in heaven. Their choices do not diminish the Godhood of Jesus Christ. Their choices to do not diminish His greatness and glory. To suggest that they are His spirit brothers and sisters, or that Satan is also His spirit brother, does not suggest that Jesus is somehow tainted by them. On the contrary, Christ suffered for all men, that if they would repent, they could be forgiven and return to live with God some day. He begs all men, no matter how sinful, to come unto Him and be healed. He suffered their sins, and knows their sins. But although He suffered those sins, He himself was without sin.
I hope that you will ask any questions that you may have about this subject, and I will try my best to answer them.