The Book of Mormon talks a lot about the concept of cursing as well as blessing. In fact, this is a major subject of the Book. The Book of Mormon begins with a great covenant from the Lord that "Inasmuch as ye shall keep my commandments ye shall prosper in the land; but inasmuch as ye will not keep my commandments ye shall be cut off from my presence." This is the great covenant of blessing and cursing in the Book of Mormon.
The Book of Mormon gives several examples of blessing and cursing beginning with Adam and the curse upon all mankind because of his transgression in the Garden of Eden. The curse is the effects that are passed down onto the children by a decision made by a parent. Because of the choice of Adam and Eve, all man will die. That doesn't seem fair because each one of us are not given the same choice Adam and Eve were, yet all are subject to the consequences.
Then there is the cursing of Laman and Lemuel who rejected the commandments of God and Nephi's leadership. The Book of Mormon mentions that Laman and Lemuel and their children were cursed and developed a darker or black skin. Many look at this detail as evidence that the Book of Mormon is racist and leads the LDS church to be racist against those of darker skin color.
Jacob 3: 8-9 O my brethren, I fear that unless ye shall repent of your sins that their skins will be whiter than yours, when ye shall be brought with them before the throne of God. Wherefore, a commandment I give unto you, which is the word of God, that ye revile no more against them because of the darkness of their skins; neither shall ye revile against them because of their filthiness; but ye shall remember your own filthiness, and remember that their filthiness came because of their fathers.
But, if you read the above passages, it is clear that the cursing was not the black skin. Black skin became a mark that was associated with the curse, but not the curse itself. The curse according to the Book of Mormon was that because of disobedience, Laman and Lemuel and their descendants, were cut off from the presence of the Lord. That curse was perpetuated to the children of Laman and Lemuel because their children were taught to be idle, iliterate and superstitious and to reject the principles of civilized living. This lack of civility, or "wicked traditions of their fathers" prevented the descendants of Laman from having the same opportunity to accept or reject Christ that Laman and Lemuel had.
So, what about the Black skin? God does not care about what skin color we are. The Book of Mormon and the Bible teach that God is no respecter of persons. And the Book of Mormon demonstrated that many Lamanites with their black skin were more valiant in their faith in Christ than any Nephite ever was (Hel. 15: 8,10, Alma 23: 6).
2 Ne. 26: 33 For none of these iniquities come of the Lord; for he doeth that which is good among the children of men; and he doeth nothing save it be plain unto the children of men; and he inviteth them all to come unto him and partake of his goodness; and he denieth none that come unto him, black and white, bond and free, male and female; and he remembereth the heathen; and all are alike unto God, both Jew and Gentile.
3 Ne. 6: 14 And thus there became a great inequality in all the land, insomuch that the church began to be broken up; yea, insomuch that in the thirtieth year the church was broken up in all the land save it were among a few of the Lamanites who were converted unto the true faith; and they would not depart from it, for they were firm, and steadfast, and immovable, willing with all diligence to keep the commandments of the Lord.
Alma 27: 27. And they were among the people of Nephi, and also numbered among the people who were of the church of God. And they were also distinguished for their zeal towards God, and also towards men; for they were perfectly honest and upright in all things; and they were firm in the faith of Christ, even unto the end
The Lamanites were cursed in that Laman rejected the gospel of Jesus Christ and the culture of industry and agriculture. The Lamanites resorted to an idle hunting-gathering lifestyle and from being exposed to the elements, sun, and eating a diet of raw meat; their skin darkened. Also, when the Lamanites mixed seed with the other Native Americans who where already present, and adopted their culture (wicked traditions), black skin is a dominant trait so all the Lamanite children would be dark skinned. So, when the Nephites saw the children of Laman and Lemuel they were surprised at the change in their appearance and associated the skin with the curse.
The curse was that the Lamanites in their aboriginal state were not as blessed as the Nephites who had accepted the fullness of the gospel and the culture of hard work, literacy, agriculture, industry, and civility that go along with it. Thus all the Nephite children had the same opportunity to accept of reject the gospel of Christ while the Lamanite children did not.
The Book of Mormon talks about marking as a sign of a curse and not the curse itself. There is the example of the Amlicites who painted their foreheads red. Amlici rejected the principles of democtratic and representative government and sought to be made king over the Nephites. Amlici drew away many supporters and the political division that resulted developed into a civil war. Recognizing their weakness, Amlici joined with the Lamanites to battle against the main body of Nephites. To help distinguish themselves from the other Nephites in battle, the Amlicites marked themselves painting their foreheads red. Mormon comments how this marking was in fulfillment of the prophecy that anyone who rejects Christ and accepts the incorrect traditions of the Lamanites would be cursed as well.
Some believe at the Tower of Babel everyone's languages were all of the sudden confounded all at once. The scripture doesn't necessarily say that. It says that the people were scattered and their language was confounded. I don't think this happened all at once.
So, how does this relate to the cursing of Black skin? I don't think it necessarily was an all of the sudden thing. I am of the opinion that in consequence of rejecting Christ, and knowledge of industry and agriculture, and adopting an idle, superstitious, hunter-gatherer lifestyle that those the skin of the Lamanites turned dark because they were out in the elements and the sun in conjunction with their diet. Also, because the Lamanites likely mixed with the other Native American's, their children would have had darker skin because darker skin is a dominant trait.
The dark skin itself isn't the curse on the African or Lamanite people. It may be a mark or result of it. Any curse of the African race, like the curse of Adams transgression is the consequences that parent's sin left to their children.The only curse on the African race was their adoption of a culture of a hunter-gathering and superstition. This isn't limited to the African race. The conseqences of this lifestyle is that it takes so much effort for hunter-gatherers to get enough food that there is no time to ponder about spiritual things (Maslow's hierarchy).
So, the culture of hunting-gathering prevented the Lamanites and Africans from learning about Christ and being blessed by that knowledge. So, the blessing of wheat, corn and other cash crops is not only that they could support large populations, but that they gave man leisure time. And with that leisure time, man could pray and read scriptures and learn about God and Christ. On the other hand, according to Maslow, if a man is constantly worried about shelter and food; it doesn't leave him time to concern himself with higher, spiritual needs.
The curse is lifted once a people accept a culture which allows facilitates literacy, learning, industry, and agriculture. Remember that there is no reason there should be hunter-gathers in the first place. Able had been taught agricultural practices and to cultivate. Cain was a hunter but could have benefited from Abel's garden. But, Cain killed Abel and left the family to live on his own. Thus the Earth had its first culture of hunting and gathering.
Then came the mark of black skin which became a mark associated with the curse, but the skin itself is not the curse. When the Book of Mormon says that in the Last days the Lamanites skin will be fair and delightsome. It's not saying that their skin will change color. It is talking about that they will adopt a culture of civilization which will enable them to accept Christ.
Moro. 9:12 And only a few years have passed away, and they were a civil and a delightsome people (notice how Mormon substitutes civil for the word fair).
A major theme of the Book of Mormon talks about the wicked priests of Noah being exiled, stealing new wives of the Lamanite daughters, eventually integrating with the Lamanites and being made teachers over the Lamanites. Teaching them to read and write and to engage in trade. The literacy of the Lamanites then made it possible for the Nephites to take the Brass Plates and preach to the Lamanites and convince them of the incorrect traditions of their fathers (hunting and gathering).
So, because of literacy and free trade, the gospel of Jesus Christ was spread and many Lamanites came to a knowledge of Christ. We see the same influences on civilization today. Literacy and Free Trade will soon open up China to the preaching of Christianity as it has many other countries.
So, in the end, the curse isn't the black skin. The black skin is only a mark of the curse. The curse is the rejection of literacy, industry, agriculture, and civilization. We see many in the inner-city reject literacy and industry and they mark themselves with markings which reflect their gang and ghetto culture. Other anti-civilization groups mark themselves in other ways. Homosexual males mark themselves by speaking with an effeminate voice.
So, if having black skin does not mean that a person is less valiant or less worthy in the eyes of the Lord, or is cursed by God; then why did the LDS church not allow Black males to receive the priesthood? The answer is, I don't know. Another speculative answer is the subject of other posts, but it more had to do with God making allowance for the learned racism of my parents and grandparents than it did the unworthiness or cursed status of the Black race.
How can we learn from the principle of cursing and marking today? The United States is fighting a culture war (Bill OReily). This is not a black and white war. This war is a civilization vs. law of the jungle war. As it relates to inner-city poverty; inner-city poverty is not a black issue. It is a ghetto culture issue that is white, Asian, Hispanic, and black. Ghetto culture romanticizes and legitimizes a negative culture of materialism and sexual immorality that results in illegitimacy and poverty. There are many other examples like religious extremism. Those of us in the civilized world need to preserve the principles of literacy, industry, learning, agriculture, religious liberty which will allow our children the same opportunities that we have had to accept or reject Christ. Again and again the Book of Mormon and Bible prophets and Apostles tell us the "stand fast in the liberty wherewith Christ hath made us free" (Gal. 5: 1, Mosiah 23: 13, Alma 58: 40, Alma 61: 9, 21, Hel. 15: 8).