The Book of Mormon was written for our day. It carries a message confirming that Jesus is the Christ, the Son of the Living God. One of the major themes of the Book of Mormon, other than the saving and exalting power of the Savior Jesus Christ, is pride. The Lord told the early saints of the restored church: "Beware of pride, lest ye become as the Nephites of old" (D&C 38:39). We are to learn from the mistakes of the Nephites and not become prideful as they became. One doesn't have to look hard to find numerous scriptures about pride. Because the Book of Mormon was written for us, this major theme is telling about the sins of our day. The apostle Paul also taught about the last days: "In the last days perilous times shall come. For men shall be lovers of their own selves, covetous, boasters, [and] proud" (2 Tim. 3:1-2). Paul goes on to list more sins of those who live in the last days but he starts out with pride.
The more I read the Book of Mormon, the more convinced I am that pride is at the root of all, or almost all, sins. While pride itself is not the most grievous sin (see Jacob 2:22), it leads to a multitude of other sins. Mormon noted this about the Nephites' pride: "they did wax stronger and stronger in their pride, and in their wickedness" (Hel. 11:37). Note that in this verse, as with the words of Paul, pride came first. This is also noted in the book of Helaman. There was a time of peace and prosperity. The Nephites expanded their lands and spread the gospel - many thousands were baptized. All seemed well in Zion. In fact, it was noted that there "was no contention among the people of Nephi save a little pride which was in the church (Hel. 3:1; emphasis added). As the chapter progresses the people become more and more prideful, which leads those who are prideful to persecute the humble followers of Christ. After a few years there was great wickedness throughout the members of the church: "And it came to pass that the fifty and second year ended in peace also, save it were the exceedingly great pride which had gotten into the hearts of the people; and it was because of their exceedingly great riches and their prosperity in the land; and it did grow upon them from day to day" (Hel. 3:36).