The following is a brief overview of the beliefs of Mormonism (The Church of Jesus Christ of Latter-Day Saints) believe, along with what the Bible really teaches, printed among the many articles and resources in the back of the ESV Study Bible (posted with permission).
1. Apostasy and Restoration
Mormons claim that “total” apostasy overcame the church following apostolic times, and that the Mormon Church (founded in 1830) is the “restored church.”
If the Mormon Church were truly a “restored church,” however, one would expect to find first-century historical evidence for Mormon doctrines like the plurality of gods and God the Father having once been a man. Such evidence is completely lacking.
Mormons believe that humans, like God the Father, can go through a process of exaltation to godhood.
But the Bible teaches that the yearning to be godlike led to the fall of mankind (Gen. 3:4ff.). God does not look kindly on humans who pretend to attain to deity (Acts 12:21-23; contrast Acts 14:11-15). God desires humans to humbly recognize that they are his creatures (Gen. 2:7; 5:2; Ps. 95:6-7; 100:3). The state of the redeemed in eternity will be one of glorious immortality, but they will forever remain God’s creatures, adopted as his children (Rom. 8:14-30; 1 Cor. 15:42-57; Rev. 21:3-7). Believers will never become gods.
5. Jesus Christ
Mormons believe that Jesus Christ was the firstborn spirit-child of the heavenly Father and a heavenly Mother.
Jesus then progressed to deity in the spirit world.
He was later physically conceived in Mary’s womb, as the literal “only begotten” Son of God the Father in the flesh (though many present-day Mormons remain somewhat vague as to how this occurred).
Biblically, however, the description of Jesus as the “only begotten” refers to his being the Father’s unique, one-of-a-kind Son for all eternity, with the same divine nature as the Father (see note on John 1:14; cf. John 1:18; 3:16, 18; see also John 5:18; 10:30).
And Mary’s conception of Jesus in his humanity was through a miracle of the Holy Spirit (Matt. 1:20).
6. Three Kingdoms
Mormons believe that most people will end up in one of three kingdoms of glory, depending on one’s level of faithfulness. Belief in Christ, or even in God, is not necessary to obtain immortality in one of these three kingdoms, and therefore only the most spiritually perverse will go to hell.
Mormons believe that God gives to (virtually) everyone a general salvation to immortal life in one of the heavenly kingdoms, which is how they understand salvation by grace. Belief in Christ is necessary only to obtain passage to the highest, celestial kingdom—for which not only faith but participation in Mormon temple rituals and obedience to its “laws of the gospel” are also prerequisites.