From Jeff Lindsay, a member of the Church of Jesus Christ of Latter-Day Saints and administrator of a popular Mormon apologetics website:

Accounts of three major migrations from the Old World to the New World are provided in the Book of Mormon. Most of the text consists of records maintained by the Nephite people, which descended from a group that left Jerusalem in 600 B.C. That group, consisting of the family of Lehi and others, split into two rival groups which became known as the Nephites (descended from Nephi) and the Lamanites (descended from Laman, eldest son of Lehi). These groups seem to have gained strength and numbers by incorporating (possibly conquering?) other diverse peoples in the area, as anthropologist John Sorensen ably documents in his article, "When Lehi's Party Arrived in the Land, Did They Find Others There," Journal of Book of Mormon Studies, 1(1): 1-34 (1992), Foundation for Ancient Research and Mormon Studies, Provo, Utah.

In the Book of Ether, a condensed account is offered of the ancient Jaredites, a people which escaped the dramatic changes occurring at the time of the tower of Babel. They were led by the Lord to construct unique, sealed vessels (with provisions for ventilation and miraculous provisions for lighting) in which they traversed the Atlantic to the New World, establishing a civilization that could correspond with or be tied to the Olmecs (based on the stimulating analysis of Dr. John Sorensen in his monumental book, An Ancient American Setting for the Book of Mormon, Deseret Book Comp., S.L.C., UT, 1985. This civilization showed marked differences in culture and government compared to the Nephites and Lamanites, though they suffered similar destruction in the end. The story is a stunning tragedy of man's rejection of God.

Another migration to the New World occurred around 588 B.C. when some survivors of the Babylonian invasion of Jerusalem (including Mulek, of royal blood) fled to the New World (details are not provided - the journey may have been made with the help of Phoenician sailors). The Mulekites had been on their own for several generations when the Nephites joined forces with them....

The Book of Mormon people had a marvelous understanding of the role of Christ as Savior. Before His mortal ministry, many Book of Mormon people (or at least the more spiritually oriented ones) understood that the sacrifices of the law of Moses were a symbol of the Messiah who would be crucified. Prophets taught that the plan of salvation for humankind was only possible through the Atonement of Christ, in which the demands of justice were satisfied by the infinite sacrifice of the pure and holy Messiah, thus bringing about mercy. This plan of redemption brought about forgiveness of sins to those who repent and accept Christ, following Him.

The highlight of the Book of Mormon is the ministry of the Resurrected Christ to the Book of Mormon peoples - Nephites and Lamanites. (Chapter 11 of Third Nephi begins the account of the ministry of Christ to the Lamanites and Nephites.) He brought His Gospel in its fullness to these people, taught them the Sermon on the Mount, blessed their children, gave authority to chosen disciples to baptize and administer the sacrament, organized His Church, and ushered a fallen society into a golden era of 200 years of peace.

Note that, according to Mr. Lindsay, God could be merciful only after he vented his just rage by mercilessly torturing the body of a man who was strong enough to take it. This is what Mr. Lindsay calls "atonement," "in which the demands of justice were satisfied by the infinite sacrifice of the pure and holy Messiah, thus bringing about mercy."

And note that not just Mormons but evangelical "Christians" like Mike Huckabee--and many other American "Christians," under all sorts of labels including "Catholic"--accept and indeed celebrate this particular notion of "atonement."

If you believe that reconciliation with God, and reconciliation with other people, could have been magically instituted by the torture and murder of one guy in the desert 2,000 years ago; and if you believe that you can "have" this reconciliation simply by saying that you "believe" in the saving power of this murder; then you already believe in the worst kind of black magic. And to explain this magical transmission of peace, worldwide, through one splendid killing, you are going to have to devise--consciously or unconsciously--absurd fantasies like the ones we see in the Book of Mormon about angels and Israelites flying or floating all around the world.

It could be said that the Book of Mormon articulates the unconscious presuppositions of most versions of "Christianity" in the United States.