"Therefore, all the Lamanites who had become converted unto the Lord did unite with their brethren, the Nephites, and were compelled, for the safety of their lives and their women and their children, to take up arms against those Gadianton robbers, yea, and also to maintain their rights, and the privileges of their church and of their worship, and their freedom and their liberty." (3 Nephi 2:11,12)
Throughout the history recorded in the Book of Mormon, we see lots of wars and contentions amongst the Nephites and the Lamanites. The feud started back when Lehi first brought his family out of Jerusalem into the wilderness, when Laman and Lemuel, his oldest two sons, were angry. Then, when they came to the promised land, what is now known as the American continents, Laman figured he would receive his birthright, being the oldest son. But, Nephi, the youngest and most righteous son, got it instead. This furthered the contention that already existed amongst the brothers, and caused a rift between them, and created the two classes: Nephites and Lamanites. The Nephites were usually the more righteous, having the gospel with them, whereas the Lamanites took after the wicked traditions of their fathers. However, Nephites were not immune to temptations, and would often fall into wickedness, whereas Lamanites weren't immune to the Spirit, and many converted to the gospel, and were righteous. It was often said that, come the judgment, it would be better for the Lamanites because they didn't have the light and knowledge that the Nephites had, and sinned in ignorance. This rivalry kept up until the bitter end, when Moroni alone was righteous amongst the people.
However, despite this long standing rivalry, they put aside their differences when a problem arose. They were sick of the Gadianton robbers and all their pillaging and plundering. The Lamanites were righteous, as were the Nephites, and they banded together and put their faith in the Lord, crying out in prayer for his help, and they were able to defeat the Gadianton robbers, though it took a few years.
We must be willing to do the same. The work cannot progress singlehandedly. No one person can save the world, it takes a team. Even Batman teamed up and joined the Justice League, and even Wolverine was part of the Avengers. But besides just teaming up, we have to be willing to work with anyone, so long as the goal is common. If you have a similar goal, who cares how you're different. One of my former companions was pretty much my polar opposite: he loved sports. Sports was his life. He watched, he played, he talked about... pretty much the only thing he watched on TV was ESPN. And he didn't know a thing about music. Music is to me what sports was to him: my life! Music was the center of pretty much everything for me. How could we possibly get along? Well, we did. Very well, too. For 3 months we were companions, and now I definitely count him as one of my best friends.
A common goal must unite us all, despite our political views, despite our differing tastes in music, movies, etc., despite our social and economical standings... let nothing tear us apart and keep us from reaching that goal. Let us put our differences aside, and work together!