Originally posted by the Darkone
Then why do Mormons believe that Lucifer and Jesus are brothers? to my understanding, and why mormons don't believe that jesus is god in the flesh and that there is a holy trinity.
We believe Christ is a son of God, the only son of God to become a God upon being spiritually formed. We believe all people are sons and daughters of God, we believe all angels to be sons and daughters of God. We believe Christ was God in the flesh, but we do not believe he was the same entity as God the Father. We believe the two to be entirely separate and distinct, being one in purpose and intent, not one in essence and substance. We believe Trinitarian doctrine to be false and a tool used by Satan to lead people away from the truth.
You must realize that Mormons do not believe God made an end of speaking to man, we believe that prophets exist today, and God speaks to them. Thus God's word is by no means limited only to the Bible, even though the Bible is the word of God insofar as it has been translated and recorded correctly.
Here is our scripture that describes what occurred in heaven:
Abraham 3:16-2816 If two things exist, and there be one above the other, there shall be greater things above them; therefore Kolob is the greatest of all the Kokaubeam that thou hast seen, because it is nearest unto me.
17 Now, if there be two things, one above the other, and the moon be above the earth, then it may be that a planet or a star may exist above it; and there is nothing that the Lord thy God shall take in his heart to do but what he will do it.
18 Howbeit that he made the greater star; as, also, if there be two spirits, and one shall be more intelligent than the other, yet these two spirits, notwithstanding one is more intelligent than the other, have no beginning; they existed before, they shall have no end, they shall exist after, for they are gnolaum, or eternal.
19 And the Lord said unto me: These two facts do exist, that there are two spirits, one being more intelligent than the other; there shall be another more intelligent than they; I am the Lord thy God, I am more intelligent than they all.
20 The Lord thy God sent his angel to deliver thee from the hands of the priest of Elkenah.
21 I dwell in the midst of them all; I now, therefore, have come down unto thee to declare unto thee the works which my hands have made, wherein my wisdom excelleth them all, for I rule in the heavens above, and in the earth beneath, in all wisdom and prudence, over all the intelligences thine eyes have seen from the beginning; I came down in the beginning in the midst of all the intelligences thou hast seen.
22 Now the Lord had shown unto me, Abraham, the intelligences that were organized before the world was; and among all these there were many of the noble and great ones;
23 And God saw these souls that they were good, and he stood in the midst of them, and he said: These I will make my rulers; for he stood among those that were spirits, and he saw that they were good; and he said unto me: Abraham, thou art one of them; thou wast chosen before thou wast born.
24 And there stood one among them that was like unto God, and he said unto those who were with him: We will go down, for there is space there, and we will take of these materials, and we will make an earth whereon these may dwell;
25 And we will prove them herewith, to see if they will do all things whatsoever the Lord their God shall command them;
26 And they who keep their first estate shall be added upon; and they who keep not their first estate shall not have glory in the same kingdom with those who keep their first estate; and they who keep their second estate shall have glory added upon their heads for ever and ever.
27 And the Lord said: Whom shall I send? And one answered like unto the Son of Man: Here am I, send me. And another answered and said: Here am I, send me. And the Lord said: I will send the first.
28 And the second was angry, and kept not his first estate; and, at that day, many followed after him.
The first was Christ, the second was Lucifer, Satan, the Devil, whatever you choose to call him. Satan was cast out due to his desire to usurp God's power:
Doctrine and Covenants 29:3636 And it came to pass that Adam, being tempted of the devil—for, behold, the devil was before Adam, for he rebelled against me, saying, Give me thine honor, which is my power; and also a third part of the hosts of heaven turned he away from me because of their agency;
And then from the LDS Bible dictionary:
Bible Dictionary, excerpt from the entry on the DevilThe devil is the enemy of righteousness and of those who seek to do the will of God. Literally a spirit son of God, he was at one time “an angel” in authority in the presence of God; however, he rebelled in the premortal life, at which time he persuaded a third of the spirit children of the Father to rebel with him, in opposition to the plan of salvation championed by Jehovah (Jesus Christ). “Thus came the devil and his angels” (D&C 29: 37). They were cast out of heaven, and were denied the experience of mortal bodies and earth life (Isa. 14: 12-15; Rev. 14: 4-9; 2 Ne. 2: 17; 2 Ne. 9: 8; D&C 29: 36-38; D&C 76: 25-26; D&C 93: 25; Moses 4: 1-4; Abr. 3: 27-28).