The fall of Adam brought about the conditions of mortality.  It brought physical death which is the separation of the physical body and the spirit.  It also brought spiritual death or separation from God.  Without divine intervention, mankind could not be saved from these consequences.

Jesus Christ's atonement rescues us from each of these conditions.  Because of his death and resurrection, all mankind will be resurrected or have their physical bodies and spirits reunited after death.  Through his suffering for our sins in the Garden of Gethsemane, all men can also be saved from spiritual death or be brought back into communion with God and be exalted if they so choose.  Mankind can live in the hope of a better life here and in the world to come.

Jesus Christ was chosen in the premortal world as part of God's plan to be the Savior of the world.  In order to fulfill his divine role, he had to be sinless, and he had to voluntarily give his life, even though he had the power to save himself (1).  The atonement of Christ is the greatest expression of both our Heavenly Father's and Jesus Christ's love for us.

To be exalted and saved from spiritual death, men must believe in God and his plan.  They must have faith in the Savior, knowing that through him they can be forgiven.  They must repent of their sins.  They must accept his gospel and receive baptism and all of the other ordinances God has given to bring us to him.  Then they must endure to the end in keeping the covenants made in each of these ordinances and growing toward perfection.

1  The Articles of Faith by James E. Talmage, pages 77-80.​

(For additional insights, read The Articles of Faith by James E. Talmage.)