2 Nephi 9 Nephi's little brother, Jacob, has grown up and has been called to be a prophet. He talks about the role of the Atonement of Jesus Christ in the plan of salvation plus temporal and spiritual death.
Temporal (or physical) death is the separation of the tangible body from the spirit. Because of the Fall of Adam, all who are born on this earth will die temporally 2 Nephi 9:6. Spiritual death is more serious and is separation from the presence of God. Again, because of the Fall of Adam, we are separated from the actual, physical presence of God, which gets worse when we sin Romans 3:23; Alma 12:16; Helaman 14:18.While all will be experience the resurrection of the physical body, if the gift of repentance is not utilized, the death of the spirit remains permanent. No unclean thing can dwell with God. Sadly, we all have to live somewhere. If it is not with God, it is with the adversary 2 Nephi 9:12–13, 22, 2 Nephi 9:6–9, 2 Nephi 9:10.
When the Savior submitted to the will of the Father, He overcome temporal death and spiritual death for Himself and all the inhabitants on the earth from the beginning until the mission of the earth is fulfilled 2 Nephi 9:5–7, 12, 21–22; Luke 22:44; Mosiah 3:7; D&C 19:16–19.
Jacob teaches us what must be done to be “saved in the kingdom of God.” We must believe in Jesus Christ, the Holy One of Israel, and come unto Him 2 Nephi 9:18, 23–24, 41. We must endure the crosses of the world and despise the shame of the world (2 Nephi 9:18; Matthew 16:24; 3 Nephi 12:29–30; 2 Nephi 9:49. We must hearken to the voice of the Lord 2 Nephi 9:21; D&C 1:38; 18:33–36; 88:66. We must repent, be baptized, and endure to the end 2 Nephi 9:23–24. We must choose to be spiritually minded 2 Nephi 9:39; Romans 8:5–8. We must feast upon the words and will of Christ, which do not perish 2 Nephi 9:50–51. In this feasting, we must remember His words so we can use them to pattern our lives and help us make right choices. 2 Nephi 9:52; 3 Nephi 15:1 We must pray always 2 Nephi 9:52. This is the plan of happiness. Although we will experience trials in this life, we can still find constant happiness and joy through Jesus Christ. While we may experience tangible and temporal blessings, the most significant blessings of earth life are to be led to know joy by understanding the plan of happiness.