When the plan for our salvation was presented to us in the spirit world, we were so happy that we shouted for joy (see Job 38:7).
We understood that we would have to leave our heavenly home for a time. We would not live in the presence of our heavenly parents. While we were away from them, all of us would sin and some of us would lose our way. Our Heavenly Father knew and loved each one of us. He knew we would need help, so he planned a way to help us.
We needed a Savior to pay for our sins and teach us how to return to our Heavenly Father. Our Father said, "Whom shall I send?" (Abraham 3:27). Two of our brothers offered to help. Our oldest brother, Jesus Christ, who was then called Jehovah, said, "Here am I, send me" (Abraham 3:27).
Jesus was willing to come to the earth, give his life for us, and take upon himself our sins. He, like our Heavenly Father, wanted us to choose whether we would obey Heavenly Father's commandments. He knew we must be free to choose in order to prove ourselves worthy of exaltation. Jesus said, "Father, thy will be done, and the glory be thine forever" (Moses 4:2).
Satan, who was called Lucifer, also came, saying, "Behold, here am I, send me, I will be thy son, and I will redeem all mankind, that one soul shall not be lost, and surely I will do it; wherefore give me thine honor" (Moses 4:1). Satan wanted to force us all to do his will. Under his plan, we would not be allowed to choose. He would take away the freedom of choice that our Father had given us. Satan wanted to have all the honor for our salvation.
Bruce R. McConkie, Mormon Doctrine, p. 750. "Our spirit bodies had their beginning in pre-existence when we were born as the spirit children of God our Father. "