“Before you were born on the earth, you lived in the presence of your Heavenly Father as one of his spirit children.” (True to the Faith: A Gospel Reference, p. 115)
In Genesis 2:7, we are told that God created Adam from the dust of the earth. He was not a pre-existing soul. Rather, he had life breathed into him. That is the precise moment when Adam's life began. He did not exist prior to walking in the Garden of Eden.
In Genesis 5:3, we are told that Adam had a son in his own image and likeness named Seth. Thus, he had life breathed into him just as did his father. Seth never existed in the form of a disembodied soul prior to his birth.
In 1 Corinthians 15:46-47, the Apostle Paul states that our physical birth takes place prior to our spiritual birth. This is contrary to the idea of our souls being pre-existent. God breathed life into man when he was created from the dust of the ground, not put already existing souls into bodies.
Jesus Christ as God existed eternally with the Father. He took on flesh to make atonement for our sins. If our souls are pre-existent, then that would compromise the uniqueness of Christ. There would be no basis for Him to appeal to His pre-existence as a special qualification (John 8:56-58). The response to Christ's claims of being God points to a general absence of belief in all human souls being pre-existent amongst Jews of His day (John 8:59).
Blake T. Ostler
notes the following regarding the absence of belief in the preexistence of human souls amongst the earliest followers of Mormonism:
"The earliest Mormon publications defined God—in terms borrowed from contemporary orthodox Christianity—as the sole and necessary basis of all existence.2 [See, for example, Apostle Parley P. Pratt’s statement that at death the human spirit “return[s] to the fountain and become[s] part of the great all from which [it] emanated,” in Parker Pratt Robinson, Writings of Parley P. Pratt (Salt Lake City: Robinson, 1952), 216.] The concept of a preexistence either in the sense of eternal, uncreated spirits co-existing with God or as spirit offspring of God did not exist in early Mormon thought. The Book of Mormon assumed that human existence depended entirely upon God (see, for example, Mos. 2:20-21). When the premortal Lord revealed his finger to the brother of Jared, he explained that humans were created “in the beginning after mine own image … after the body of my spirit” (Eth. 3:15-16), implying that human, physical bodies resemble God’s spiritual body. In contrast, orthodox Christianity interpreted “image and likeness” (Gen. 1:26) [p.128]to mean humankind’s moral capacities, not its physical attributes. The seeds, at least, of anthropomorphism and of co-existence of humans with God were thus planted in Mormon thought in the Book of Mormon notion of creation after the image of God’s spiritual body."
The same cited source also said the following regarding the pre-existence of man being foreign to early Mormon thought:
"The classical gulf between God and his mortal creations entailed in the doctrine of creatio ex nihilo was accepted without revision in the official Mormon publication The Evening and the Morning Star in October 1832: “The Creator, who having created our souls at first by an act of his will can either eternally preserve them or absolutely annihilate them” (p. 77). Humans were thus contingent beings who did not exist prior to their creation by God—either as body or as spirit—and could lapse into non-being if God willed it. A letter in the May 1835 Latter Day Saints’ Messenger and Advocate echoed a similar belief: “Man is dependent on the great first cause and is constantly upheld by Him, therefore justly amenable to him” (p. 113)."
