God's love remains with Israel, not Edom.
God rebukes the priests for offering blemished sacrifices on His altar, yawning and mocking at the routine and paltry worship.
The priests used to preserve knowledge, by now you are leading people astray, and going astray yourselves.
The messenger of the covenant is coming to refine you Levites.
The reason you aren't consumed already is because I am unchangeable in My mercy to you in spite of your stubbornness all along.
You rob Me by not giving Your full tithe. You speak against Me by speaking ill of serving Me.
God-fearers unite and write down their obedient desires. God recognizes and promises to honor it.
The distinction will be clear again when the day comes. The wicked will burn like stubble, but the righteous will burst out in joy.
Remember Moses and his law.
Elijah will come to you before the day of the LORD to turn fathers to their children again, before destruction comes.
How this is about Jesus
He is the messenger of the covenant who comes and cleanses His priests and His temple.
John wears Elijah's clothes, and announces the coming of Jesus.
The back-and-forth of Malachi ("how have we hated You?") shows that believers can backslide and not even realize it. We must stay diligent in our walk with the Lord. Give God your best in worship.