Originally posted by divegeester
I'm sure this will have come up before.
"Then the Lord put a mark on Cain so that no one who found him would kill him" (Genesis 4:15-16)
I've read that some institutions such as the Mormons for example, believe that the mark was dark skin colour The Mormons also believe that if a person of 'dark skin colour' becomes a LDS their skin gradually light ...[text shortened]... therefore cursing him the associated affliction of the inevitable racism is the answer.
Wikipedia says this. It reports that Mormonism adopted the general white Protestant belief so it should not be construed as unique to Mormonism, although
"Like many Americans of the era, Mormons of the 19th century commonly assumed that Cain's "mark" was black skin, and that Cain's descendants were black and still under Cain's mark. Mormonism began during the height of white Protestant acceptance of the curse of Cain doctrine in America, as well as the even more popular curse of Ham doctrine, which was even held by many abolitionists of the time. This belief seemed to be confirmed by a scriptural passage in the Book of Abraham which suggested that Cain's bloodline was preserved on the ark through Egyptus, wife of Ham, (an interpretation now generally rejected by mainstream Mormons). While Joseph Smith indicated his belief in the curse of Ham theory in a parenthetical reference as early as 1831, the only early reference to the curse or mark of Cain was in the Joseph Smith Translation of the Bible, which included the following statement:
And Enoch also beheld the residue of the people which were the sons of Adam; and they were a mixture of all the seed of Adam save it was the seed of Cain, for the seed of Cain were black, and had not place among them.
There is evidence that Joseph Smith did not consider the restriction between blacks and the priesthood to be relevant in modern times, since he himself (and other church leaders close to him) did ordain black men to the priesthood. notably Elijah Abel and Walker Lewis."
The reference  refers one to a speech attributed to Brigham Young.
That speech says, in part:
" Now then in the kingdom of God on the earth, a man who has has the Affrican blood in him cannot hold one jot nor tittle of preisthood; Why? because they are the true eternal principals the Lord Almighty has ordained, and who can help it, men cannot. the angels cannot, and all the powers of earth and hell cannot take it off, but thus saith the Eternal I am, what I am, I take it off at my pleasure, and not one partical of power can that posterity of Cain have, until the time comes the says he will have it taken away. That time will come when they will have the privilege of all we have the privelege of and more. In the kingdom of God on the earth the Affricans cannot hold one partical of power in Government. The the subjects, the rightfull servants of the resedue of the children of Adam, and the resedue of the children through the benign influence of the Spirit of the Lord have the privilege of seeing to the posterity of Cain; inasmuch as it is the Lords will they should receive the spirit of God by Baptisam; and that is the end of their privilege; and there is not power on earth to give them any more power."
Of course all the above is just what Wikipedia and its reference  say. It also discusses how this belief has been moderated since then.