"A prophecy: The word of the LORD to Israel through Malachi. 'I have loved you,' says the LORD." — Malachi 1:1-2a
The name Malachi means "my messenger." God has a message for his people, and he wants to make sure they take it seriously from the start. This is a prophecy, God says; this is my word through my messenger. God even uses his covenant name, which in the Hebrew text is YHWH (Yahweh). In English we often render it as "the LORD" (with small capital letters). This is the name God used to describe himself when he made a covenant with his people through Moses (see Ex. 3:10-20). Then, in the message through Malachi, God adds again, "says the LORD," making clear that this is important.
So what is this important message that God makes such a big deal of? Very simply, it is "I have loved you."
God's love is the most important message of the entire Bible, and God's love is the central message of Malachi. God loves us.
Throughout the rest of the book God's people ask him a lot of questions. And behind each one they are wondering, "How have you loved us?" God always has an answer, and he has never once let his love slip, not even for a moment.
God loves you, even if you aren't sure that he does. Even if you don't really know him yet. Even if you know him but have been resisting him or living in rebellion against him. He still loves you, and he very much wants you to know that.