In Mormonism, every human being existed before birth as a spirit child of Heavenly Parents. These spirit children were organized from eternal “intelligences” and given spirit bodies made of refined matter. God the Father, Heavenly Mother, Jesus, and all humans share this same essential nature, differing only in degree of progression.
Earth life is seen as a necessary stage in which spirit children receive physical bodies and are tested, with the goal of eventually becoming like their Heavenly Parents.
Biblical Christianity teaches that human life begins at conception, not in a premortal realm. God alone is eternal and uncreated (Psalm 90:2). People are his creatures, not his literal offspring in a heavenly sense. Our relationship to God comes through faith in Christ, who makes us his children by adoption (Galatians 4:4–5).
