Madeleine said:
One problem that I can think of off the top of my head with a "racist" Lehi: "Race" is a ~17th century invention.
I absolutely agree. David Goldenberg (book referenced below) makes an excellent case for this. In that sense I am convinced that the passages in the Book of Mormon dealing with 'dark skin' as a curse or 'sign' of the curse, is totally anachronistic. It shouldn't be there. If Nephi and Lehi really did exist then the idea of God cursing a group of people with a dark skin would be totally alien to them. It makes no sense. The only way it does make sense is if it is Joseph Smith's ideas rather than any ancient group. Sylvester Johnson (book referenced below) outlines just how familiar what is found in the Book of Mormon would have been in 19th Century America in particular. Whites were the superior race, chosen of God, the Native American Indian was ungodly, far from the Christian God, and the blacks were even further down the pecking order with some viewing them as less than human.
Regarding the mark of Cain...it was formulated by people who were pro-slavery as a pseudo support for slavery. Pseudo, because it isn't a real argument. As you have already pointed out, Genesis says nothing of Cain's skin color changing.
Also, it was an attempt to define the differences in race from a biblical perspective. In 19th Century America, (and before) the world was viewed through a biblical lens in Christian countries. Interestingly Muslim slave traders used the same justification (curse of Ham/Canaan) for their trading in slaves.
They were reading in to the text what just wasn't there, in order to justify their own worldview and practices.
Modern Biblical scholars place the passage in the culture from which it comes, and speculate it was a tattoo. Also, the mark wasn't a curse but a sign of being protected by God.
Yes, it almost certainly wasn't a change in skin colour since Israelites were from the same tribal base as the Canaanites. Joseph Smith wouldn't have appreciated or understood this.
Curse of Ham : Race and Slavery in Early Judaism, Christianity and Islam
Goldenberg, David M.
Pages: 468
Publisher: Princeton University Press
Location: Princeton, New Jersey, USA
Date Published: 07/2005
Myth of Ham in Nineteenth-Century American Christianity : Race, Heathens, and the People of God
Johnson, Sylvester
Pages: 204
Publisher: Palgrave Macmillan
Location: Gordonsville, VA, USA
Date Published: 12/2004
"It's a little like the Confederate Constitution guaranteeing the freedom to own slaves. Irony doesn't exist for bigots or fanatics." Maksutov