Every major difference between Mormonism and biblical Christianity ultimately comes back to one question: what is the authority by which we know what is true? For evangelical Christianity, the answer is Scripture alone — the 66 books of the Old and New Testaments, complete, sufficient, and final. For Latter-day Saints, the answer is Scripture plus — the Bible (with reservations), the Book of Mormon, the Doctrine & Covenants, the Pearl of Great Price, and the ongoing declarations of a living prophet.
This is not a minor procedural difference. It is the foundation beneath every other difference. Once you accept that there can be new scripture, new revelation, and a living prophet who speaks with divine authority, then the God who was once a man, the Jesus who is Lucifer's spirit-brother, and the salvation that requires temple ordinances all become possible — because the authority to teach them exists outside of and above the Bible. Remove that additional authority structure, and the entire LDS theological edifice collapses back to the Bible alone — and the Bible alone will not support a single major LDS doctrine.
The Bible: Accepted "As Far As It Is Translated Correctly"
The LDS church's eighth Article of Faith states: "We believe the Bible to be the word of God as far as it is translated correctly; we also believe the Book of Mormon to be the word of God." That phrase — as far as it is translated correctly — is doing enormous theological work. It functions as a standing escape clause: any biblical passage that contradicts LDS teaching can be dismissed as a translation error, without providing any textual evidence for the claim.
This is worth pressing in conversation. The Bible is one of the most thoroughly documented ancient texts in human history. We have over 5,800 Greek manuscripts of the New Testament — more than any other ancient document by orders of magnitude. The science of textual criticism has given us extremely high confidence in the text of Scripture. When an LDS believer claims a passage was "mistranslated," the appropriate question is: which manuscript? Which early translation? Where is the evidence?
The LDS church has its own "inspired" revision of the Bible — the Joseph Smith Translation (JST) — in which Smith altered hundreds of passages. But the JST is based on no ancient manuscripts whatsoever. Smith did not examine Greek or Hebrew texts. He simply revised the King James Version according to his own claimed revelations. This is not translation. It is rewriting.
The Closed Canon: Scripture Was Finished
The biblical case for a closed canon — that divine revelation to humanity through inspired Scripture is complete — rests on several converging lines of evidence.
Jude 3: The Faith Once Delivered
The phrase "once for all delivered" uses the Greek hapax paradotheise — delivered once, completely, at one definitive moment. The faith is not an ongoing, accumulating body of revelation. It was delivered — past tense, completed action — to the saints. Jude's urgent warning to contend for it implies it is something that can be corrupted or lost, not something that is still being added to.
Revelation 22:18–19: Do Not Add
Latter-day Saints often respond that this warning applies only to the book of Revelation, not to the whole Bible. This is technically possible in a narrow literary sense, but it misses the force of the passage. Revelation is the capstone of the entire biblical canon, bringing together the threads of prophetic literature from Genesis onward. The warning at the end of the last book of the Bible carries symbolic as well as literal weight. More importantly, the same principle is stated at the beginning of the canon: Deuteronomy 4:2 says "You shall not add to the word that I command you."
Galatians 1:8–9: Anathema on New Gospels
As we noted in Article 1, Paul's warning in Galatians 1:8–9 is the most directly applicable passage to the Mormon situation. Paul uses the hypothetical of "an angel from heaven" bringing a different gospel — precisely the mechanism by which the Book of Mormon was supposedly delivered (by the angel Moroni). Paul pronounces a curse on any such addition. This is not ambiguous language.
The Book of Mormon: Historical and Archaeological Problems
The Book of Mormon claims to be a history of ancient civilizations in the Americas — the Jaredites (who migrated from the Tower of Babel), and the Nephites and Lamanites (who migrated from Jerusalem around 600 BC). It describes sophisticated cities, a literate culture, massive armies numbering in the hundreds of thousands, and a complete civilization with horses, steel swords, chariots, wheat, barley, and cattle.
The archaeological and scientific problems with this account are comprehensive and devastating.
No Archaeological Evidence
Despite 190 years of searching by believers and secular scholars alike, no archaeological evidence has ever been found for any of the civilizations described in the Book of Mormon. The Smithsonian Institution and the National Geographic Society have both issued formal statements clarifying that they have found no evidence supporting the historical claims of the Book of Mormon. No cities, no artifacts, no inscriptions, no burial sites — nothing corresponding to cultures of the size and sophistication described.
By contrast, the biblical cities, peoples, and events described in the Old and New Testaments have been extensively confirmed by archaeology. The contrast could not be starker.
Anachronisms: Things That Didn't Exist
The Book of Mormon describes numerous elements that archaeology and biology confirm did not exist in pre-Columbian America during the time periods described:
Horses — described repeatedly (1 Nephi 18:25, Alma 18:9, etc.). Horses went extinct in the Americas approximately 10,000 years ago and were not reintroduced until the Spanish arrived in the 1500s. There are no pre-Columbian depictions of horses in the Americas.
Steel and iron — described as widespread (1 Nephi 4:9, Jarom 1:8). Metallurgy of this kind did not exist in the pre-Columbian Americas.
Wheat and barley — described as crops (Mosiah 9:9). These Old World grains were not present in the pre-Columbian Americas.
Chariots — described in Alma 18:9–10. No wheeled vehicles existed in pre-Columbian Mesoamerica.
Elephants — mentioned in the Jaredite narrative (Ether 9:19). While mammoths existed in the Americas, they were extinct thousands of years before the Jaredite period described.
The LDS church's current approach is to suggest that the Book of Mormon's geography is uncertain and that anachronisms may reflect "translation challenges" — that Smith translated concepts into the nearest English equivalent even if imprecise. This response essentially concedes that the text is not a reliable historical record of actual civilizations. It also contradicts Joseph Smith's own confident historical claims about the text. Be ready for this pivot: it is an admission of the problem dressed in theological language.
DNA Evidence
The Book of Mormon implies a significant Middle Eastern (Hebrew) population in the pre-Columbian Americas. Decades of DNA studies on Native American populations have consistently shown that their origins trace to East Asian and Siberian peoples who migrated across the Bering land bridge — not to Middle Eastern populations. The LDS church has acknowledged this problem in a Gospel Topics Essay, now suggesting that the Lehite migration involved a small group that may have been "absorbed" into existing populations — a significant retreat from the text's own claims.
The Book of Abraham: A Documented Failure
In 1835, Joseph Smith acquired Egyptian papyri and claimed to translate them as the writings of the patriarch Abraham. The resulting text became the Book of Abraham, now part of the Pearl of Great Price and considered canonical LDS scripture. It contains significant theological material used to support LDS doctrines including the pre-mortal existence and the nature of God.
In 1966, the original papyri were rediscovered in the Metropolitan Museum of Art in New York. Multiple qualified Egyptologists — including LDS scholars — examined them. Their conclusion was unequivocal: the papyri are standard Egyptian funerary documents, specifically a portion of the Book of Breathings — a common Egyptian text concerned with mummification and the afterlife. They have nothing to do with Abraham. Smith's "translation" bears no relationship whatsoever to what the documents actually say.
"I've been reading about the Book of Abraham — the one Joseph Smith translated from Egyptian papyri. When Egyptologists examined those same papyri in the 1960s, they said the translation was completely wrong. The church has addressed this in a Gospel Topics Essay. Have you read it? What did you make of it?" This is a documented, verifiable problem that the LDS church itself acknowledges — and it invites them to engage their own church's response.
The Living Prophet: A Shifting Foundation
One of the most significant practical issues with LDS theology is the authority of the living prophet. Current LDS president Russell M. Nelson speaks with the same authority as Joseph Smith — his words carry scriptural weight and can, in principle, contradict or supersede previous teaching. This has happened repeatedly in LDS history: polygamy was commanded, then banned; Black men were excluded from the priesthood for 130 years, then granted it in 1978; various theological positions have been quietly shelved or revised.
This is not a mark of a reliable divine source. The God of the Bible does not give revelation that He later needs to revise. His word endures forever (Isaiah 40:8; 1 Peter 1:25). A prophetic tradition that has required this many course corrections is by its own stated standard — Deuteronomy 18:22 — a tradition that cannot be reliably trusted.