It's important to note that "the priesthood" in the Mormon faith is every adult male[1]; so by not permitting Blacks into the priesthood, they were basically not permitted in the church at all.
The Mormon faith was founded in 1830s New York (shortly after slavery was abolished in that state), long before efforts to redefine racial relations and blacks as humans. It isn't very fair of you to project your 19th century politics back on the creators of a <200 year old religion.
> so by not permitting Blacks into the priesthood, they were basically not permitted in the church at all.
That is a wild and incorrect jump to make. Why do Mormons go to church? What are you referencing the physical buildings used or something else?
The thing is, often people will say that Mormons are racist towards blacks until 1978 and if you ask why they usually don't know. Sometimes, they'll reference the Priesthood and if you ask what that is, they usually don't know.
From your comment, unless your answers to my questions indicate otherwise, I would say you do not understand. There is so much that people do not understand in regards to this topic yet they feel valid to proclaim others as being racist.
"The Lord had cursed Cain’s seed with blackness and prohibited them the Priesthood." - Brigham Young (second LDS prophet, 1847-77).
Note that "the priesthood" is considered a requirement for salvation, so denying blacks the priesthood was quite significant. Various LDS sources seem to disagree as to why this is; Joseph Fielding Smith (10th LDS prophet, 1970-72) claimed it's because blacks didn't fight on God's side in a war during the pre-mortal existence, while Gordon B. Hinkley (15th LDS prophet, 1995-2008) simply says "I don't know".
The official position of the LDS church now is that blacks are fully equal to whites: "Forget everything that I have said, or what President Brigham Young or President George Q. Cannon or whomsoever has said in days past 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. We get our truth and our light line upon line and precept upon precept. We have now had added a new flood of intelligence and light on this particular subject, and it erases all the darkness and all the views and all the thoughts of the past. They don't matter any more." (Bruce R. McConkie, member of the Quorum of the Twelve -- basically, the lesser prophets one step below the top guy. 1978.) When he says "forget all I said" he's referring to his 1958 comments affirming the view that blacks were less valiant in the pre-mortal war [0].
EDIT: to be totally fair, despite institutionalized LDS racism, they were strongly anti-slavery in the early years; LDS founder Joseph Smith ran for president as an abolitionist in 1850.
This isn't really the place for an in-depth discussion of Mormon doctrine (and I don't really have the time today), so feel free to email me if you would like to continue the conversation.
But I will quickly correct a few of the mistakes in this conversation:
* There were black members of the Church before the lifting of the ban on the priesthood.
* Though Brigham Young characterized the priesthood ban as a "cursing" he was very clear that the priesthood would be available to people of African decent at some point in the future.
* Not being ordained to the priesthood never meant that blacks would be excluded from salvation. Through the practice of proxy ordinances for the dead, Mormon doctrine has always made clear that all would have the chance at salvation even if denied the opportunity to have the priesthood during this life.
* Limiting the priesthood, or even the preaching of the gospel, to a specific family is part of the Biblical pattern in both the Old and New Testaments.
* Though there was clearly some racism in the Mormon Church before 1978 (and probably still is today), the people I know who were part of the church at that time say it was limited. The official position then, as it is now, was of love and acceptance within the limitations they felt the Lord had set.
Conversations such as this one are valuable, but be aware that they tend to oversimplify complex topics.
A great book on the topic written by a black Mormon who joined the Church before 1978 is this one:
While the Bible definitely shows a pattern of preaching to specific groups, as soon as there's an organized religious system, there's a method for outsiders to receive full benefits. Moses allowed foreigners to participate in passover (Ex 12:48) and other sacrificial ordinances (Ex 22:18). While certain rites were only performed by priests, who were from a particular family, the benefits of those rites applied to everyone in the nation (see Num 15:25-26). Likewise, immediately after Jesus' resurrection, both Jewish and non-Jewish believers received the same spiritual gifts (Acts 10:45) and the same salvation (Rom 1:16, Gal 3:28).
Interestingly, the early LDS allowed blacks full membership with no limitations (for example, Elijah Abel was a black LDS priest in 1832.) The Book of Mormon describes blacks as cursed (2 Nephi 5:21) but allowed to come to the Lord just like anyone else (2 Nephi 26:33). And it makes the anti-racism statement "revile no more against them because of the darkness of their skins" (Jacob 3:8-9). Joseph Smith himself was an abolitionist (D&C 101:79).
But Brigham Young declared that if Utah received statehood, it wouldn't be Congress' business whether or not they had slaves or how they treated them (Journal of Discourses 4:39-40). He also stated that the penalty for mixed marriage is death on the spot (JoD 10:110), and that blacks couldn't hold the priesthood until after all of the whites did, at which point they would actually turn white (JoD 7:290, 337). Wilford Woodruff (4th LDS prophet) said that the only way someone in a mixed marriage could have salvation was to be beheaded, and for all of his children to be killed as well; there's no "proxy baptism" option present here.
By the 1950s, the common view was that blacks were cursed because they had not behaved valiantly in the pre-mortal existence, but that they would eventually receive full blessings. Then in 1978 a "revelation" allowed blacks to hold the priesthood. There are still some vestiges of the 1950s view, though; a friend told me of someone else in his mission who, after visiting a non-committal black family, complained that "n___ers were fence-sitters in the pre-existence and they're fence-sitters now".
So, as you say, it's complex. Official LDS doctrine (specifically coming from "prophets") regarding blacks went from a little racist to extremely racist to kinda racist to not racist. Individual LDS attitudes have always had some variability.
The cynic & atheist in me thinks that "Mormon beliefs followed contemporary conservative US attitudes" to be a much more accurate, succinct and possibly honest description of the situation. Racist when it was common to be racist, not racist once that got politically unacceptable.
A similar timeline happened with polygamy/plural marriages. Abandoned when it became politically unacceptable.
Your version isn't actually very accurate. In particular, note that official Mormon doctrine was at times much more racist and at other times less racist than contemporary conservative US attitudes, with significant changes from one "prophet" to the next. I wouldn't characterize it as following others attitudes, but rather as being controlled by the whims of individual men who were all over the spectrum of US attitudes, and who didn't particularly agree with each other.
Your comment on polygamy is also lacking sufficient detail. In particular, note that LDS polygamy was never convenient or accepted by outsiders; whenever it was publicly known, it led to serious community opposition, and probably contributed to their being chased out of Nauvoo [2]. They also officially denied practicing or teaching polygamy, even as Joseph Smith was accumulating a total of 34 wives [0]; he was actually killed as a result of fallout from burning the printing press that was used to expose the practice [1]. Even their "abandoning the practice" was more of a denial that it ever happened, and a weak bit of "advice" to "refrain" from violating local laws [3]. This came shortly after serious attempts by the US government to end polygamy via asset seizures and other forms of pressure; unlike in the 1850s, there were few uncolonized areas they could move to (but some LDS fled to Mexico, including some of Mitt Romney's ancestors [4]). So it would be more accurate to say that the practice was officially abandoned when it became exceedingly difficult to continue. Even so, unofficially within the main LDS church and officially within various offshoots, polygamy continues to this day [5]; official doctrine still teaches polygamy in the afterlife as well [6].
[5] My friend Doris Hansen escaped from fundamentalist Mormon polygamy, and now runs a ministry to rescue other women and children: http://www.shieldandrefuge.org/index.htm . The ministry has its own TV show at http://whatloveisthis.tv/ . The show archives contain lots of interviews with former polygamist men and women.