Our purpose on Earth can best be understood by knowing how things went from easy to not-so-easy.
When God the Father created Adam and Eve, He placed them in the Garden of Eden and gave them two commandments. One was to multiply and replenish the earth, and the second was to not partake of the fruit of the tree of knowledge of good and evil. Most Christians believe that the Fall was a mistake; this the Mormons refute because of new revelation given in the Book of Mormon. In that Book, the prophet Lehi taught that had Adam and Eve not transgressed (eaten the fruit) they would have remained in the Garden of Eden in a stagnant state of no progression - no knowing good or evil because they were innocent. Because of their eating of the fruit, however, they were cast out of the Garden of Eden to toil and work all their days, which would be filled with opposition to promote growth and learning (see 2 Nephi 2 in the Book of Mormon). Thus, according to the Gospel of Jesus Christ, the Fall of Adam was paramount to our coming to Earth.
THE BLOOD ATONEMENT AND RESURRECTION
In addition to pain and suffering, sin and death also entered the world through the Fall of Adam and Eve. Because of our being mortals, we cannot rid ourselves of our sin, nor can anything sinful enter the presence of God. There must be a way for this to occur, however. But, what is the way? Only through Jesus Christ the Savior.
He, Jesus Christ, volunteered and was ordained before the world was made to be our Savior - to free us from death unconditionally and from sin if we would follow Him. He did free us from sin on the condition that we repent when He suffered in the Garden of Gethsemane, bleeding from every pore, as well as when He died on the Cross of Calvary. He was able to do this for us because He is a God.
Three days later, He rose from the tomb as "the first begotten of the dead (Rev. 1:5)", to use John's phrase. As this "first begotten" God, He freed all people from death. We will no longer have to suffer throughout eternity without our bodies, but will live again as He did! What joyous proclamations should be heralded throughout the wide expanse of all the earth!!! Freedom from death!!! Those fathers and mothers, husbands and wives, brothers and sister, sons and daughters who die, and whose siblings and spouses and parents mourn, will truly have their tears wiped away because of the Lord that is faithful!!! If they repent while in the flesh, they shall live with their families throughout eternity. This binding of families is made available in Holy Temples, 130 of which are operating at furious rates.
So, I say to all, come unto Christ the Lord and His only true Church. Come unto the Authority that binds forever and ever and you will be saved!! This I declare in the sacred name of Jesus Christ, Amen