The charge that Latter-day Saints aren't Christians often rests on fairly obvious fallacies of equivocation.
Such fallacies occur when an essential term is used twice (or more) in an argument, but in shifting senses.
One popular illustration of the fallacy was supplied by the late Irving Copi: "Criminal actions are illegal, and all murder trials are criminal actions; thus, all murder trials are illegal." Obviously, the term "criminal actions" is used with two different meanings, and the argument is bogus.
My favorite specimen, though, is this one, in which "all the world" is used equivocally:
I love you.
Therefore, I am a lover.
All the world loves a lover.
You are all the world to me.
Therefore, you love me.
How do those claiming that Mormons aren't Christians often commit a fallacy of equivocation? A common argument runs this way:
Mormons aren't Christians. Why? Because Mormons differ dramatically from the Christian mainstream, rejecting major doctrines (for example, the Nicene Trinity) that developed in the centuries after Christ.
Critics often accuse us of deceptively claiming to be traditional Christians, and puzzled outsiders sometimes ask why we claim to be Christians while rejecting certain doctrines and traditional creeds.
But we don't claim to be mainstream Christians, and these objections conflate or confuse "mainstream Christianity" or "traditional Christianity" or "historical Christian orthodoxy" with "Christianity" as a whole. They mistakenly assume that "Christianity" and "mainstream Christianity" are synonyms.
Obviously, the two are related. But they aren't the same — just as "box" and "cardboard box" aren't synonymous. (There are, after all, wooden, glass, metal, stone, plastic, and other kinds of boxes.) A cardboard box is a type of "box," but a person who doesn't want a cardboard box isn't necessarily rejecting boxes altogether. Likewise, a squirrel is a species within the larger class of mammals, and Catholicism and Methodism are species or types of Christianity. There are many types of mammal besides squirrels, many types of Christian beyond Catholics and Methodists.
After endorsing Rick Perry at the "Values Voter Summit" earlier in October, Baptist pastor Robert Jeffress defended his denunciation of Mormonism with a pretty typical specimen of equivocating language: Mitt Romney, he said, is "not a Christian" because he "doesn't embrace historical Christianity."
His denunciation presumes, falsely, that "Christianity" and "historical Christianity" (the Christianity defined at Nicea and other councils) are synonymous, and that to reject the latter entails rejecting the former, too.
However, although they overlap, "historical Christianity" and "Christianity" are distinct concepts, just as palms, firs, flowering plums, and apple trees are both similar and different. Palm trees still share "treeness" with apple trees, and, for that matter, with trees generally. They differ merely in secondary traits.
We Latter-day Saints cheerfully acknowledge — indeed, we proclaim — that our faith isn't part of the traditional Christian mainstream. After all, if it were mainstream there would have been no need for the Restoration or the mission of Joseph Smith.
At the same time, we also strongly affirm our Christianity, our faith in Jesus Christ as the divine Son of God and Redeemer who offers humans their only hope of salvation.
These two positions — our insistence that we're Christians and our simultaneous denial that we're members of the Christian mainstream — aren't mutually contradictory, because they affirm and deny different things.
The Church of Jesus Christ of Latter-day Saints — which some call the Mormon church — declares itself a restoration of New Testament Christianity, distinct from all other types of Christianity but still very strongly asserting the deity and atoning mission of Jesus of Nazareth. While it isn't a branch of the main trunk of creedal Christendom, its roots — like those of that main trunk — emerge undeniably from the soil of early Christianity.
Others certainly dispute the Mormon self-understanding, but there can be no dispute that believing Mormons hold it, and that they place all their hope for eternal life in the Atonement of Jesus Christ.
That Mormonism is neither Catholic, Orthodox nor Protestant; that Mormons hold distinctive beliefs; that we don't share some of the doctrines of other Christians — these are surely matters of secondary importance when discussing whether or not Mormonism is Christian.
Joseph Smith's declaration cannot be recalled too frequently in this context: "The fundamental principles of our religion," he said, "are the testimony of the Apostles and Prophets, concerning Jesus Christ, that He died, was buried, and rose again the third day, and ascended into heaven; and all other things which pertain to our religion are only appendages to it."
Daniel C. Peterson is a professor of Islamic studies and Arabic at BYU, where he also serves as editor in chief of the Middle Eastern Texts Initiative and as director of advancement for the Neal A. Maxwell Institute for Religious Scholarship. He is the founder of MormonScholarsTestify.org.