Mormons annoy evangelicals by refusing to agree to the inerrancy of the Bible, believing that book is correct only so far as it is translated correctly. Most mainstream Christians agree with modern scholars that since we do not have original sources of any biblical text and variations exist among available sources, no translation can be presumed to record exactly what was in the original.
Although siding with scholars on problems of biblical inerrancy, Mormons tend to favor the notion of the inerrancy of modern revelation. Yet Joseph Smith, at least as recorded in HC4:61, never claimed the Book of Mormon was perfect. His words were “it is the most correct of any book.” Certainly the title page acknowledges the possibility of errors, “if there are faults they are the mistakes of men. . . .” Church leaders have authorized several changes in the Book of Mormon within my lifetime—dropping some of the repetitions of, “And it came to pass” in 1st and 2nd Nephi and softening the language describing Lamanites as filthy and loathsome people. The D&C has also had revisions—the entire Lectures of Faith being removed from the text in 1921.
A recent blog about the writings of Joseph Smith describes George A. Smith, Church Historian in the 1850s, gathering (correlating?) Joseph Smith’s speeches from notes recorded in journals and letters written at the time. George A. apparently felt authorized to add material he remembered or thought the prophet said (or should have said) to the written sources. Since source materials were recorded informally by untrained people, and Joseph did not generally speak from a written text, we cannot be sure of the accuracy of our written versions of the speeches he made. And this is within relatively recent times where the speaker and most of the hearers were literate and attempts to record speeches were made at the time they were given.
How much more problematic are the speeches of Jesus. Probably none of his disciples was literate—literacy at that time was limited to a small fraction of the population. Acts tells us the disciples were “unlearned and ignorant men” (4:13). Because ancient writers often signed their works with the names of more prominent people—a clever marketing strategy— contemporary scholars do not believe Matthew and John were written by the actual apostles. Most believe the earliest parts of the New Testament are the seven epistles considered to have actually been written by Paul. These letters are generally dated about 50 CE. Mark, the earliest of the gospels, is dated about 70 CE, and John, the latest, about 90 CE.
The lack of eyewitnesses recording events at the time makes it unlikely that any of Jesus’s speeches were recorded verbatim. At best, our Bible contains what people writing many years later remembered or had heard from others. Basing one’s faith on a text with such shaky claims to accuracy seems risky to me—kind of like building a house on a sand foundation.
That said, I’m not implying that scriptures, modern or ancient, have no value for contemporary readers. I do believe, however, that readers are best served by reading scriptures with an understanding of the time and culture in which they were written. And I suspect the parts of the scriptures most likely to have been remembered and recorded accurately are the stories, parables, and poetry because these forms of literature not only stick in our memories, they speak to our hearts.