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Mormonismo e Assuntos Raciais/Negros e do sacerdócio/Idéias repudiou/Neutro em "guerra no céu"
Tópicos do Evangelho: "Hoje, a Igreja nega as teorias do passado para que a pele escura é um sinal de desagrado divino ou maldição, ou que ela reflete as ações de uma vida pré-mortal; que casamentos interraciais são um pecado; ou que os negros ou as pessoas de qualquer outra raça ou origem étnica são inferiores de qualquer forma a qualquer outra pessoa"
"As Etnias e o Sacerdócio," Tópicos do Evangelho em LDS.org:
Hoje, a Igreja nega as teorias do passado para que a pele escura é um sinal de desagrado divino ou maldição, ou que ela reflete as ações de uma vida pré-mortal; que casamentos interraciais são um pecado; ou que os negros ou as pessoas de qualquer outra raça ou origem étnica são inferiores de qualquer forma a qualquer outra pessoa. Os líderes da Igreja hoje inequivocamente condenam todo racismo, passado e presente, sob qualquer forma.23
Desde aquele dia, em 1978, a Igreja olhou para o futuro, enquanto os membros entre africanos, afro-americanos e outras pessoas de ascendência africana continua a crescer rapidamente. Enquanto os registros da Igreja para os membros não indicam raça de uma pessoa ou origem étnica, o número de membros da Igreja de descendência africana chega agora a centenas de milhares de pessoas.
A Igreja que proclama essa redenção por meio de Jesus Cristo está disponível para toda a família humana sobre as condições que Deus determinou. Ela afirma que Deus “não faz acepção de pessoas”24 e declara enfaticamente que qualquer pessoa que é justa — independente de raça — é favorecida por Ele. Os ensinamentos da Igreja em relação aos filhos de Deus são abrangidos por um versículo no segundo livro de Néfi: “[O Senhor] não repudia quem quer que o procure, negro e branco, escravo e livre, homem e mulher; (…) todos são iguais perante Deus, seja judeu ou gentio. —(Clique aqui para continuar) 
Joseph Fielding Smith: "We know of no scripture, ancient or modern, that declares that at the time of the rebellion in heaven that one-third of the hosts of heaven remained neutral"
We know of no scripture, ancient or modern, that declares that at the time of the rebellion in heaven that one-third of the hosts of heaven remained neutral. ... That one-third of the hosts of heaven remained neutral and therefore were cursed by having a black skin, could hardly be true, for the negro race has not constituted one-third of the inhabitants of the earth. —(Clique aqui para continuar) 
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.
Question: Did Church leaders ever teach that Blacks were neutral in the "war in heaven?"
Yes, some Church leaders promoted the idea as a way to explain the priesthood ban
Despite the explicit denial of this concept by Brigham Young, the idea that people born with black skin as a result of their behavior in the pre-existence was used by several 20th century Church leaders in order to try and provide an explanation for the priesthood ban.
The First Presidency, in a statement issued on August 17, 1949, actually attributed the ban to "conduct of spirits in the premortal existence"
The First Presidency stated in 1949:
The position of the Church regarding the Negro may be understood when another doctrine of the Church is kept in mind, namely, that the conduct of spirits in the premortal existence has some determining effect upon the conditions and circumstances under which these spirits take on mortality. 
Joseph Fielding Smith said in 1954 that there were no "neutrals in the war in heaven," but that rewards in this life may have "reflected actions taken in the pre-existence
In the 1954 book Doctrines of Salvation (compiled by Bruce R. McConkie), Joseph Fielding Smith stated that "there were no neutrals in the war in heaven," but suggested that the rewards received in this life reflected actions taken in the pre-existence:
NO NEUTRALS IN HEAVEN. There were no neutrals in the war in heaven. All took sides either with Christ or with Satan. Every man had his agency there, and men receive rewards here based upon their actions there, just as they will receive rewards hereafter for deeds done in the body. The Negro, evidently, is receiving the reward he merits. 
Bruce R. McConkie said in 1966 that they were "less valiant" in the pre-existence
The most well known of these was the statement made by Bruce R. McConkie in his book Mormon Doctrine. McConkie offered the following opinion:
Those who were less valiant in the pre-existence and who thereby had certain spiritual restrictions imposed upon them during mortality are known to us as the negroes. Such spirits are sent to earth through the lineage of Cain, the mark put upon him for his rebellion against God and his murder of Abel being a black skin...but this inequality is not of man’s origin. It is the Lord’s doing, based on His eternal laws of justice, and grows out of the lack of spiritual valiance of those concerned in their first estate. 
These statements by Church leaders reflected ideas which were prevalent in society during the 1950s and 1960s
These statements by 20th century leaders did not represent thinking that was unique to the Church, but instead reflected ideas which were much more prevalent in society during the 1950's and 1960's.
When the priesthood ban was lifted in 1978, McConkie retracted what he had said previously
Elder McConkie retracted his previous statements regarding the priesthood ban when it was lifted in 1978:
Forget everything I have said, or what...Brigham Young...or whomsoever has said...that is contrary to the present revelation. We spoke with a limited understanding and without the light and knowledge that now has come into the world. 
Question: Did the Church repudiate the idea of neutrality in the "war in heaven?"
President Kimball was reported as repudiating this idea following the 1978 revelation
Some members and leaders explained the ban as congruent with the justice of God by suggesting that those who were denied the priesthood had done something in the pre-mortal life to deny themselves the priesthood. President Kimball was reported as repudiating this idea following the 1978 revelation:
President Kimball "flatly [stated] that Mormonism no longer holds to...a theory" that Blacks had been denied the priesthood "because they somehow failed God during their pre-existence." 
The modern Church rejects this theory
Today, the Church disavows the theories advanced in the past that black skin is a sign of divine disfavor or curse, or that it reflects actions in a premortal life; that mixed-race marriages are a sin; or that blacks or people of any other race or ethnicity are inferior in any way to anyone else. Church leaders today unequivocally condemn all racism, past and present, in any form. 
Modern Church leaders teach that everyone who came to earth in this day was "valiant" in the premortal existence
Elder M. Russell Ballard, talking of today's youth, said in 2005:
Remind them that they are here at this particular time in the history of the world, with the fulness of the gospel at their fingertips, because they made valiant choices in the premortal existence. 
- "As Etnias e o Sacerdócio," Tópicos do Evangelho em LDS.org (2013)
- Joseph Fielding Smith, "The Negro and the Priesthood," Improvement Era Vol 27, Num 6, pg 565 (April 1924)
- 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.
- First Presidency Statement (George Albert Smith), August 17, 1949. off-site
- Joseph Fielding Smith, Doctrines of Salvation (Salt Lake City: Bookcraft, 1954) , 1:65-66. (emphasis in original)
- Bruce R. McConkie, Mormon Doctrine (1966), p. 527.
- Bruce R. McConkie, "New Revelation on Priesthood," Priesthood (Salt Lake City: Deseret Book, 1981), 126-137.
- Kimball, Lengthen Your Stride, chapter 24, page 3; citing Richard Ostling, "Mormonism Enters a New Era," Time (7 August 1978): 55. Ostling told President Kimball's biographer and son that this was a paraphrase, but an accurate reporting of what he had been told (see footnote 13, citing interview on 10 May 2001).
- "Race and the Priesthood," Gospel Topics, lds.org. (2013) off-site
- M. Russell Ballard, "One More," Ensign, May 2005, p. 69.