In Mormon 4:12, Mormon makes an interesting statement regarding the degree of wickedness to which the Nephites and Lamanites had sunken to:
And it is impossible to describe, or for man to write a perfect description of the horrible scene of the blood and carnage which was among the people, both of the Nephites and the Lamanites; and every heart was hardened, so that they delighted in the shedding of blood continually.
And there never had been so great wickedness among all the children of Lehi, nor even among all the house of Israel, according to the words of the Lord, as was among this people. (Mormon 4:12-13)
According to Douglas and Robert Clark, this statement can hardly be appreciated without reading the Old Testament's descriptions of the appalling degradation that had set in on the kingdom of Judah just prior to the Babylonian destruction. The only thing in history known to compare with the Nephite wickedness is the infamous generation of the flood, whose degradation, depravation, and refusal to repent were similar to that of the Nephites (see Genesis 6:5, 11-13; Moses 7:32-41; 8:18-30) -- and brought a similar result: total annihilation. [E. Douglas Clark and Robert S. Clark, Fathers and Sons in the Book of Mormon, p. 237]