Elder Uchtdorf's devotional talk at BYU Education Week focused on Mosiah 18:21, one of the favorite passages in the Book of Mormon.
Mosiah 18:21 also happens to be a focus of understanding the translation. Here is an excerpt from my book, A Man that Can Translate. I developed this approach in much more depth in my latest book, Infinite Goodness, which focuses on non-biblical intertextuality.
In my view, the appearance of non-biblical intertextuality is solid evidence that Joseph Smith actually translated the engravings on the plates.
p. 225. ... passages in the text include bits of New and Old Testament phrases joined together to compose a single verse in the Book of Mormon. Royal Skousen describes this as “blending.”
[Blending] is quite different from a paraphrastic quoting of a single King James passage (or a midrash-like commentary on it). It is as if the translator knows the King James Bible so well that hardly anything can be translated without using biblical phrases and expressions. Thus the Book of Mormon translation is much more than a literal rendition of what was originally on the plates. It is a highly creative translation affected by a thoroughly absorbed knowledge of the King James Bible.
The concept of blending is comparable to the concept of chunking. In both cases, the author or speaker rearranges terms, phrases and concepts drawn from his/her mental language bank to express his/her thoughts that often have little or nothing to do with the original source.
The blending in the Book of Mormon is fluid. The manuscripts show no evidence of trial-and-error dictation or collaboration. And this is exactly how language works in our minds. We formulate thoughts by arranging and rearranging chunks of language we have heard or read elsewhere, converting those chunks into our own unique expressions.
The first example of blending Skousen offers is from Mosiah 18:21, “having their hearts knit together in unity and in love one towards another.”
This passage contains the only usage of the term knit in the Book of Mormon. The term appears seven times in the KJV. Three of these involve the term heart(s).
Epistle Dedicatory. “is that which hath so bound and firmly knit the hearts of all Your Majesty’s loyal and religious people unto You…”
1 Chronicles 12:17. “If ye become peaceably unto me to help me, mine heart shall be knit unto you…”
Colossians 2:2. “That their hearts might be comforted, being knit together in love…”
Skousen demonstrates the blending this way:
Skousen points out that other writers used similar phrases.
1652, John Clarke, “and had their hearts knit together in a more than ordinary bond of love.”
1656, Alexander Grosse, “and to have our hearts knit together in love.”
Of course, both of these authors postdated the 1611 King James Version and the Epistle Dedicatory, so they represent blending of biblical passages themselves.
There is another element of Mosiah 18:21 that has a relationship to a Biblical passage. The phrase “in unity” appears only once in the Book of Mormon and once in the Bible. Psalm 133:1 reads, “Behold, how good and how pleasant it is for brethren to dwell together in unity!”
Adding this passage to the blending gives us a more complete accounting for the passage:
Whether he composed the text or translated it, Joseph could have blended Colossians and Psalms subconsciously, by randomly choosing passages from different parts of the Bible, or by coincidence. The combination of Old and New Testament verses is problematic for a literal translation because the Book of Mormon authors presumably had no access to New Testament texts. That’s why this is good evidence of both composition and translation. Note, however, that we still must omit much of Colossians and Psalms to make the blending work.
Skousen treats KJV blending as evidence that Joseph did not translate the text.
It is as if the translator knows the King James Bible so well that hardly anything can be translated without using biblical phrases and expressions… Each example provides an extraordinary demonstration of linguistic gymnastics. Of course, all of this is quite amazing, perhaps even miraculous, if one assumes that Joseph Smith must have been the one responsible for all of this textual manipulation.
As a rule, preachers and theologians quote, paraphrase, and rearrange passages from the Bible. The blending in the Book of Mormon is different, though, in the sense that passages (chunks) of biblical and theological language are used not to borrow authority from the original, but instead to repurpose the chunks for an entirely different document. That distinction is key to understanding how Joseph translated the text.
Let’s start with Jonathan Edwards, the “father of American theology.” He introduced Colossians 2:2 with his own preface and paraphrased the rest. Separately, he spoke of counsel to live in unity and love one another. His work offers a simpler and cleaner blending than one derived solely from the KJV.
Jonathan Edwards: “and seemed, by their discourse and behavior after public worship, to have their ‘hearts knit together in love’ Colossians 2:2.” Also: "giving of them counsel, to live in unity and love one another, as one that was going from them…”
Combining these quotations, we see a closer fit than the KJV verses, and without the omissions those verses require. Plus, the Edwards phrase starts with a form of the verb have.
To be sure, Edwards used the Bible here, but he did so in chunks, putting biblical passages in his own construction to paraphrase rather than directly quote the Bible, much the same way that the Book of Mormon does. Because the original chunks are so diverse, I suggest this blending in the Book of Mormon is not evidence of copying from the Bible (or from Edwards) but instead is evidence of composition or translation from Joseph’s lexicon, his mental language bank.
 Wilson (2012): 132.
 Skousen, Part 4 (2018): 1031.
 Skousen, Part 4 (2018): 1032.
 Skousen, Part 4 (2018): 1031.