Since Mormonism is not descended from one of the largest branches of Christianity (Roman Catholic, Eastern Orthodox, and Protestant) some Christians say that means Mormons are not Christian.

The substance of this argument is that Mormons are a “new” religion, which puts Christianity vs. Mormonism at odds. It was founded in 1830 by a farmboy named Joseph Smith. However, Mormons believe that this argument is invalid because, at one point or another, all Christian churches, including the Roman Catholic, Eastern Orthodox, and Protestant churches were “new” churches. They were all considered to be heretical by the religion they broke away from. 

Roman Catholicism and Eastern Orthodoxy grew out of Judaism. Roman Catholicism and Eastern Orthodoxy eventually split from each other based on doctrinal differences about the nature of the Trinity. Roman Catholics made a change to the Nicene Creed by adding something called the filioque. The original document said the Holy Spirit comes from the Father, the filioque added the phrase “and the Son” to the creed. Orthodox Christians believed this was an unauthorized error to the original text of the creed.   

Protestantism split from Roman Catholicism because they believed that indulgences and various other doctrines of the Roman Catholic Church were heresies. Many other Protestant religions split from the Protestantism defined by Martin Luther and began to define Christian doctrine differently from each other. None of these religions are considered non-Christian because of their break with each other, or because of their doctrinal differences. Mormons argue that they should not be excluded from the title of Christian” because they have doctrinal differences with other Christian denominations.

The major branches of Christianity see their churches as directly descended from Jesus Christ and his apostles. They don’t view Mormons as a part of the lineage. According to these major branches of Christianity, this is why Mormons are not Christians. Mormons believe their church is a restored version of Jesus’ biblical church.