Several things should be considered when looking at this claim.

The Lord Used Familiar Language in Revealing the Book of Mormon

In Doctrine and Covenants 1:24, the Lord explains that He speaks to His people "after the manner of their language," meaning He uses language they can understand. When Joseph Smith translated the Book of Mormon, he used language from the King James Bible, which was the most widely known and used version of scripture in his time. This suggests that God, in His wisdom, inspired Joseph to use KJV phrasing to make the message clear and accessible to the early Saints. This is why certain KJV expressions, including specific wording from the 1769 edition, appear in the text.

Furthermore, in Doctrine and Covenants 8, the Lord tells Joseph to "study it out" in his mind, indicating that Joseph was actively engaged in carefully considering his word choices during the translation. This shows that the inclusion of KJV language was not accidental but a thoughtful decision, part of a guided and deliberate translation process.

Author Stephen Gibson suggests:

"instances where the Book of Mormon parallels the Bible, Joseph Smith must have noted the parallels and used the King James Bible to guide him in his choice of words. If the Book of Mormon agreed with the Biblical text in meaning, he apparently utilized the Biblical text, italicized words and all. However, when the plates differed from the Biblical text, he followed the text on the plates. For example, of 433 verses of Isaiah quoted in the Book of Mormon, 46 percent are identical to those in the Bible, while 54 percent are modified to some extent.” It should be noted, however, that none of those contemporaries involved in the translation process recall Joseph consulting the Bible or any manuscripts.

Translation was Actually Revelation

This will be addressed more elsewhere. It's a fact that Joseph didn't sit at his desk with a reformed Egyptian lexicon and matching characters and deriving translations. A reformed Egyptian lexicon didn't even exist. The Book of Mormon was revealed by the “gift and power of God." That's the only description Joseph gave of the translation process.

Why Errors?

Another angle is that the presence of 1769 KJV errors might reflect the limitations of Joseph Smith’s human capacity as a translator. For believers, it’s not unreasonable to think that while the overall message of the Book of Mormon is divinely inspired, minor elements could reflect human imperfection. This idea aligns with the belief in ongoing revelation, where even prophets receive additional light and knowledge over time, clarifying earlier teachings or understandings.

Other Considerations

There are numerous accounts by those involved in the translation that say Joseph didn't access any manuscripts. So how do we reconcile those accounts with the clear examples of KJV in the Book of Mormon? It's hard to know but it seems as if they might have been wrong. Some have sought to reconcile the statements by speculating that God might have touched Joseph's memory to share the KJV passages that he had once read. Perhaps, but it's all conjecture.

There is some debate about a "tight" versus "loose" translation. Those arguing for a tight translation often look to two Book of Mormon witness statements in particular. David Whitmer & Martin Harris.

Conclusion

In summary, the presence of these KJV features can be seen not as undermining the Book of Mormon’s authenticity but as a reflection of how divine messages are often conveyed through imperfect human language and cultural context. This approach emphasizes that the translation was intended to be meaningful and accessible to Joseph’s audience, not a flawless or literal rendering from one language to another