The book of Malachi was written after the Lehites left Jerusalem. Therefore, they did not have those scriptures. Nevertheless, Jesus wanted them to have certain parts of what Malachi wrote because it fit in with the teachings he was presenting. Therefore, “it came to pass that he commanded them that they should write the words which the Father had given unto Malachi, which he should tell them.” Jesus dictated two chapters from Malachi. Our Chapter 24 (save for the introduction) corresponds to Malachi 3.
The “Lord whom ye seek” is Jehovah, and he will “suddenly come to his temple.” The temple is the dwelling of Jehovah, so it is understandable that Jehovah would come. This prophecy of the coming of Jehovah is still in the future, as we will see as the text progresses. Therefore, we should understand who the messenger might be. The simplest explanation is that it is a generic category of all the prophets who prepare God’s people for his millennial arrival. Were there to be a single person, it would have been the mortal Messiah who came to prepare for the ultimate arrival of Jehovah on earth. Although we understand that they are the same person, there is a difference between the mortal Jesus and the resurrected Jesus.
The next 3 verses clearly show that we are dealing with a description of the end of times. At that time, Jehovah will come as a refiner’s fire. A refiner’s fire does not destroy, it purifies. Hence Jehovah will be “as a refiner and purifier of silver; and he shall purify the sons of Levi.”
There will be a restitution of the pure way to worship God and live His commandments.