In Mosiah 25 we read about the different tribes, or groups of people, who make up the Nephites. There were the people of Nephi, who are literal descendants of Nephi, but there were also those who were the descendants of Jacob, Joseph, Mulek and Zarahemla, as well as many others. These peoples may have not had blood in common, but they did have one thing in common: they followed the commandants of God.
Today, there are many different people, from many different countries in the Church of Jesus Christ of Latter-day Saints. Yet, we all gather together every week, in our different meeting houses all over the world, and learn the same things. We also have more in common, as Latter-day Saints, with other Christians all over the world, with our beliefs in the Bible and in Jesus Christ. Further, we can remember that other religions believe in God, and in an afterlife that we can earn as we are good. And one step further, we know that each of the people on earth are children of our Heavenly Father, and our brothers and sisters, and as such, we should be one with them, as the Nephites were.