William E. Riter asked B. H. Roberts why the Atonement of Christ did not "wash away" the sins of Cain.
William E. Riter, Letter to B.H. Roberts, February 27, 1921, in Brigham D. Madsen, ed. 1985. Studies of the Book of Mormon by B. H. Roberts. Second ed. (Salt Lake City, UT: Signature Books, 1992), pp. 56–57, accessed July 26, 2023
"I have another question in my mind which I would appreciate very much if you could favor me with an explanation. "Why can not the Negro hold the Priesthood?" I understand that our church does not ordain a negro to the Priesthood on account of the curse put upon Caine. The question arises, "Why should this race suffer on account of Caine's sin?" On page 2 of "The Essentials of Church History" the following statement. "It was therefore essentail that a Redeemer be provided through whose atonement for the fall, all men, without regard to their belief, race or color, are entitled to come forth in the resurrection of the dead, to be judged according to their works." Through the atonement of Christ was not also the sins of Caine washed away and the heavens opened to all mankind? There has been some confusion in my mind on this subject and I would appreciate very much if you would clear it up for me."