Phil Johnson lists John MacArthur’s take on why Mormonism is not Christian:
- The issue of authority. Christians believe the Bible is God’s authoritative, inerrant, unchanging and complete self-revelation (Jude 3). Scripture is the touchstone to which all other truth-claims must be brought (Isaiah 8:20). The sole and sufficient authority by which all controversies in spiritual matters are to be determined is none other than God’s Spirit speaking through Scripture. By contrast, Mormons consider The Book of Mormon, The Pearl of Great Price, and Doctrine and Covenants as additional authoritative revelation, thereby undermining the true authority of Scripture and violating the principle of Revelation 22:18.
- The doctrine of God. Christians believe there is one God who eternally exists in three co-equal Persons: Father, Son, and Holy Spirit. Mormons reject the doctrine of the Trinity, believing that there are many worlds controlled by different gods.
- The supremacy of Christ. Christians believe Jesus Christ is pre-existent God who became a man in His incarnation while maintaining His full deity. Mormons claim Jesus was a “spirit child” of Mary and Elohim (and the brother of Lucifer) who has now been elevated to the level of deity.
- The means of justification. Christians believe justification is by grace alone, through faith alone, in Christ alone. Mormons believe a person’s works in this life will determine his or her status in the life to come, and that “salvation” is actually a progression toward godhood.