Some critics of Latter-day Saint theology concerning the personal pre-existence of all men, not Jesus merely, have argued that it is “Platonic.” Such is simply false and shows that such critics are neither aware of Platonism and/or Latter-day Saint theology. As one Evangelical Protestant and critic of LDS theology correctly noted:
The Mormon teaching on the eternity of spirits and the spirit world might make Mormonism sound something like ancient Platonism or Origenism. Yet there is a decisive difference: Mormonism regards matter and body as fundamental to all reality and so shows itself on this point to be anti-Platonic. Mormonism teaches that a material body is necessary for happiness. The devil's punishment consists in the fact that he lacks a body. The evil spirits, in seeking to possess or infest human beings, display their own awareness and they are deficient and that they need a body to inhabit. This focus extends to God himself: God the Father and Jesus Christ are exalted beings with glorified bodies of flesh and bones . . . This teaching is as firmly established as any Mormon doctrine, since it came as an integral part of Joseph Smith's original vision. ("Appendix K: Mormon Teachings on God, Cosmos, and Salvation" in Michael J. McClymond, The Devil's Redemption: A New History and Interpretation of Christian Universalism, volume 2 [Grand Rapids, Mich.: Baker Academic, 2018], ebook version)
For more on materialism in LDS theology, see the late Stephen Webb’s (Catholic) paper:
On the evidence in favour of creation ex materia and against creation ex nihilo, see:
On the necessity of maintaining the personal pre-existence of all people to preserve the true and full humanity of Jesus, see my article:
While it is true there is no explicit witness to the personal pre-existence of all people, and, in my opinion, the Christological argument outlined in my article above is the best route to go down to support it to non-LDS inquirers and opponents, the issue of Sola Scriptura will be an issue when discussing this and many other doctrines with Protestants. Be sure to read my article addressing this topic: