In the premortal spirit world, God appointed certain spirits to fulfill specific missions during their mortal lives. This is called foreordination.
Foreordination does not guarantee that individuals will receive certain callings or responsibilities. Such opportunities come in this life as a result of the righteous exercise of agency, just as foreordination came as a result of righteousness in the premortal existence.
Jesus Christ was foreordained to carry out the Atonement, becoming “the Lamb slain from the foundation of the world,” (Revelation 13:8; see also 1 Peter 1:19–21). The scriptures tell of others who were foreordained. The prophet Abraham learned about his foreordination when he received a vision in which he saw “many of the noble and great ones” among the spirits in the premortal spirit world. He said: “God saw these souls that they were good, and he stood in the midst of them, and he said: These I will make my rulers; for he stood among those that were spirits, and he saw that they were good; and he said unto me: Abraham, thou art one of them; thou wast chosen before thou wast born” (Abraham 3:22–23). The Lord told Jeremiah, “Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations” (Jeremiah 1:5). John the Baptist was foreordained to prepare the people for the Savior’s mortal ministry (see Isaiah 40:3; Luke 1:13–17; 1 Nephi 10:7–10).
The doctrine of foreordination applies to all members of the Church, not just to the Savior and His prophets. Before the creation of the earth, faithful women were given certain responsibilities and faithful men were foreordained to certain priesthood duties. Although you do not remember that time, you surely agreed to fulfill significant tasks in the service of your Father. As you prove yourself worthy, you will be given opportunities to fulfill the assignments you then received.