Jesus Christ “came into the world … to be crucified for the world, and to bear the sins of the world, and to sanctify the world, and to cleanse it from all unrighteousness; that through him all might be saved” (DC 76:41–42). The great sacrifice He made to pay for our sins and overcome death is called the Atonement. It is the most important event that has ever occurred in the history of mankind: “For it is expedient that an atonement should be made; for according to the great plan of the Eternal God there must be an atonement made, or else all mankind must unavoidably perish; … yea, all are fallen and are lost, and must perish except it be through the atonement” (Alma 34:9).

The Fall of Adam brought two kinds of death into the world: physical death and spiritual death. Physical death is separation of the body and spirit. Spiritual death is separation from God. If these two kinds of death had not been overcome by Jesus Christ’s Atonement, two consequences would have resulted: our bodies and our spirits would have been separated forever, and we could not have lived again with our Heavenly Father (see 2 Nephi 9:7–9).