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Pergunta: Foi a ideia de que os negros eram neutros na "guerra no céu" doutrina jamais oficial?
Question: Was the idea that Blacks were neutral in the "war in heaven" ever official doctrine?
The "neutral in the war in heaven" argument was never doctrine. In fact, some Church leaders, starting with Brigham Young, explicitly repudiated the idea
This idea was repudiated well before the priesthood ban was rescinded. President Brigham Young rejected it in an account recorded by Wilford Woodruff in 1869:
Lorenzo Young asked if the Spirits of Negroes were Nutral in Heaven. He said someone said Joseph Smith said they were. President Young said No they were not. There was No Nutral spirits in Heaven at the time of the Rebelion. All took sides. He said if any one said that He Herd the Prophet Joseph Say that the spirits of the Blacks were Nutral in Heaven He would not Believe them for He herd Joseph Say to the Contrary. All spirits are pure that Come from the presence of God. The posterity of Cane are Black Because He Commit Murder. He killed Abel & God set a Mark upon his posterity But the spirits are pure that Enter their tabernacles & there will be a Chance for the redemption of all the Children of Adam Except the Sons of perdition. 
The First Presidency under Joseph F. Smith also rejected this idea
there is no revelation, ancient or modern, neither is there any authoritative statement by any of the authorities of the Church … [in support of the idea] that the negroes are those who were neutral in heaven at the time of the great conflict or war, which resulted in the casting out of Lucifer and those who were led by him. 
Joseph Smith never taught the idea that those born with black skin were "neutral" during the war in heaven
Brigham Young, when asked this question, repudiated the idea. Wilford Woodruff recorded the following in his journal:
December 25, 1869: I attended the School of the Prophets. Many questions were asked. President Young answered them. Lorenzo Young asked if the spirits of Negroes were neutral in heaven. He said someone said Joseph Smith said they were. President Young said no they were not. There were no neutral spirits in heaven at the time of the rebellion. All took sides. He said if anyone said that he heard the Prophet Joseph say that the spirits of the Blacks were neutral in heaven, he would not believe them, for he heard Joseph say to the contrary. All spirits are pure that come from the presence of God. The posterity of Cain are black because he commit[ted] murder. He killed Abel and God set a mark upon his posterity. But the spirits are pure that enter their tabernacles and there will be a chance for the redemption of all the children of Adam except the sons of perdition. 
The idea that anyone who came to earth was "neutral" in the premortal existence is not a doctrine of the Church. Early Church leaders had a variety of opinions regarding the status of blacks in the pre-existence, and some of these were expressed in an attempt to explain the priesthood ban. The scriptures, however, do not explicitly state that the status or family into which we were born on earth had anything to do with our "degree of valiance" in our pre-mortal life.
Other religions would not have had reason for such a teaching because they do not believe in the pre-existence or the "war in heaven."
The scriptures themselves do not state that anyone was neutral in the pre-existence.
- Wilford Woodruff, Wilford Woodruff’s Journal, 9 vols., ed., Scott G. Kenny (Salt Lake City: Signature Books, 1985), 6:511 (journal entry dated 25 December 1869). ISBN 0941214133.
- First Presidency letter from Joseph F. Smith, Anthon H. Lund, and Charles W. Penrose, to M. Knudson, 13 Jan. 1912.
- Wilford Woodruff's Journal, entry dated Dec. 25, 1869.