1 For, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the Lord of hosts, that it shall leave them neither root nor branch.Joseph Smith History - Moroni:
5 Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord:6 And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.
37 For behold, the day cometh that shall burn as an oven, and all the proud, yea, and all that do wickedly shall burn as stuble; for they that come shall burn them, saith the Lord of Hosts, that it shall leave them neither root nor branch.Note the diferences in the first verse. The KJV verse says that day that comes shall burn the wicked. Moroni says they that come shall burn the wicked. Big difference. Someone (we can probably infer destroying angels as indicated in D&C 77:8) is going to desroy the wicked at that day. They shall have neither root nor branch, meaning they shall have no inheritance in the vineyard of the Lord (see footnote g in the KJV for branch).
38 Behold, I will reveal unto you the Priesthood, by the hand of Elijah the prophet, before the coming of the great and dreadful day of the Lord.
39 And he shall plant in the hearts of the children the promises made to the fathers, and the hearts of the children shall turn to their fathers. If it were not so, the whole earth would be utterly wasted at his coming.
The change to the fifth verse is even more significant. The Lord will reveal the Priesthood by the hand of Elijah. Which Priesthood--the Melchizedek Priesthood, specifically the sealing power that can only be exercised by someone holding that key under the Melchizedek Priesthood. The ability to bind on earth and in heaven. Without that key, we cannot hope for salvation for ourselves or our families.
The changes to the sixth verse are also very significant. Elijah's purpose is to plant in the hearts of the children the promises made to the fathers. Abraham was promised that all the world would be blessed through his seed. Abraham held the Melchizedek Priesthood. He was a follower of righteousness. His seed has the responsibility to preach the gospel to all the world. Every member of this church is either a direct descendant or adopted into the house of Israel and thereby an heir to the promises to and responsibilities of the seed of Abraham. What an awesome responsibility we have as members of the church!