In Malachi 3:1 Jesus is the messenger of the New Covenant preparing the way for GOD. Malachi 3:2 indicates Jesus’ second coming to men and in 3:3 as a refiner, he will remove sinners, so that only the righteous remains. The everlasting New Covenant stated here is established after Jesus second coming and being righteous is critical to salvation, since only the righteous will survive to the end.
Malachi 3:1-4 (GOD) Jesus God’s messenger with the new covenant
“Behold, I send my messenger, and he will prepare the way before me. And the Lord whom you seek will suddenly come to his temple; and the messenger of the covenant in whom you delight, behold, he is coming, says the LORD of hosts. 2 But who can endure the day of his coming, and who can stand when he appears? For he is like a refiner’s fire and like fullers’ soap. 3 He will sit as a refiner and purifier of silver, and he will purify the sons of Levi and refine them like gold and silver, and they will bring offerings in righteousness to the LORD. 4 Then the offering of Judah and Jerusalem will be pleasing to the LORD as in the days of old and as in former years.
Elias, Malachi 4:5-6