“Malachi prophesied that a messenger would prepare the way for the coming of the Lord. John the Baptist prepared the way for the Lord’s mortal ministry, and Joseph Smith is the messenger who prepared the way for the Second Coming” (Old Testament “Come, Follow Me” Teacher’s Manual , 226).
1 Behold, I will send my messenger, and he shall prepare the way before me: and the Lord, whom ye seek, shall suddenly come to his temple, even the messenger of the covenant, whom ye delight in: behold, he shall come, saith the Lord of hosts.
President Joseph Fielding Smith said:
“Malachi speaks of the Lord sending His messenger to prepare the way before Him, and while that does have reference to the coming of John the Baptist, it is one of those prophecies in the scriptures that has a double fulfillment. It has reference also to the coming of the Prophet Joseph Smith, because that messenger which was to come and prepare the way before Him, was to come in this day. . . .
“Malachi said the Lord would suddenly come to His temple (see Malachi 3:1). In 1830 our Savior said He would come suddenly to His temple (see D&C 36:8). That coming was for a definite purpose: To restore keys; to purge the sons of Levi; to prepare for the offering of Judah when the Jews will be cleansed of their iniquity; and to be as a refiner and purifier, bringing salvation to all men who will obey His voice.
“It is true that many even of the Latter-day Saints are looking forth to that coming of our Lord. Let us stop and reflect a moment. Has the Lord not come already suddenly to His temple to bring about these glorious purposes? Christ appeared suddenly in (the Kirtland Ohio) temple (on April 3, 1836) (See D&C 110.).”
(Doctrines of Salvation, comp. Bruce R. McConkie, 3 vols. [1954–56], 1:193; 3:12–13.)
Elder Bruce R. McConkie wrote:
“Our Lord is the Messenger of the Covenant (Malachi 3:1). He came in His Father’s name (John 5:43), bearing His Father’s message (John 7:16–17), to fulfill the covenant of the Father that a Redeemer and Savior would be provided for men (Moses 4:1–3; Abraham 3:27–28.) Also, through His ministry the terms of the everlasting covenant of salvation became operative; the message He taught was that salvation comes through the gospel covenant.”
(Mormon Doctrine, 2nd ed. , 488.)