These two verses are a beautiful tribute to King Benjamin. How he would have loved to hear these words, not because they were praise of his kingship, but even more so because he had succeeded in the one thing he wanted to really accomplish.
He was at the end of his rule, and they were thanking him. At the beginning of his speech, he mentioned rendering thanks and praise with their whole hearts (2:20), and so when the people said it was because of their faith in what the king had taught them that they had this great knowledge, it was more than just a nice recognition. Their words arose from a generosity that comes with the experience of conversion and when we think more of what other people have done for us than what we have done for them.
Do we admire and have faith in our Church leaders? Is it not important to recognize that it is because of the things that our prophet "has spoken unto us" that "has brought us to this great knowledge?" Let us personalize this. We can read what they did, but do we do the same things whenever we have this mighty change and feel wonderful blessings in our lives?
What about this "exceeding joy whereby we do rejoice?" This is another consequence. Rejoicing with such exceedingly great joy feels more than just good. It is not a matter of "Umm, that was pretty nice." There was much joyous celebration going on among Benjamin’s people.
And as a result, Benjamin took the old things that were limited and only applied to the king, all those royal prerogatives, and opened them up and extended them to all his people. Although some of them are just symbolic things, what Benjamin gave his people were essentially royal privileges. For example, it was normally only the king that was brought up from his humiliation to be ritually raised up and crowned as the new king. Benjamin said that we are all of the dust and we are all humiliated, but then we are all elevated. To us that sounds indeed like a very generous thing, but more than that, from their frame of reference, now they were all actually putting themselves in the position that the king was normally in. Usually in an ancient Israelite coronation, the king was ritually adopted by God as his son and on that day He had ritually begotten the new monarch and pronounced, "Thou art my son" (Psalms 2:7). Benjamin’s people would now all become God’s sons and daughters (5:7). And in addition, they were all going to come away from this ceremony with a new name (3:8; 5:8), while normally there was only one person who came away from a coronation with the new name, and that was the new king. In so many ways, Benjamin was helping all his people to see themselves in a different way. They were not yet ready for democracy, with all people having the duties of the governors, but a generation later, they would be ready as a people to take that political step (Mosiah 29). That is something that could be, and has been to some extent, studied in much more depth.
Book of Mormon Central, "Why Did King Benjamin Say That His People Would be Sons and Daughters at God’s Right Hand? (Mosiah 5:7)," KnoWhy 307 (May 1, 2017): "The application of these royal enthronement texts to the people themselves—making them all potentially kings and queens, sons and daughters at the right hand—makes Benjamin’s speech utterly revolutionary. In Israelite thought, Benjamin was already a royal son who was already at the right hand of God, as Mosiah soon would be. Benjamin instead taught the people about the truly royal Son and how this Son’s Atonement made it possible for all of them to become His sons and daughters and be enthroned with this Son at God’s right hand."
John W. Welch, "Democratizing Forces in King Benjamin’s Speech," in Pressing Forward with the Book of Mormon, ed. John W. Welch and Melvin J. Thorne (Provo, UT: FARMS, 1999), 110–126.