"'If you do not listen, and if you do not resolve to honor my name,' says the LORD Almighty, 'I will send a curse on you.'" — Malachi 2:2
Throughout the book of Malachi, God is called "the LORD Almighty." "The LORD" (with small capital letters) stands for God's covenant name Yahweh, and it means, "I AM WHO I AM" (Ex. 3:14). So this name, "the LORD Almighty," reminds us that God is the all-powerful, loving God who actively cares for us. In the New Testament this is captured in the words "Jesus is Lord." The supreme Lord came to rescue us, because that's the kind of God he is (see Col. 1:15-20).
Our actions, too, stem from our character, and sometimes our actions show the truth of our hearts more clearly than our words do. Malachi reminds us that our actions should come from a heart set on God. When our actions come from anywhere else, they will be cursed by God. This means they won't bring the results we were hoping for. God will intervene. Sometimes God intervenes through natural processes, bringing foolish actions to common-sense defeat or failure. And sometimes God intervenes supernaturally. God can instantly squash even the craftiest acts of rebellion.
Rather than rebel against our God and King, we ought to seek his will in prayer. He may guide us by way of Scripture or by a nudge of the Holy Spirit. He may move us to act humbly without clear direction. But he will always stand behind a heart that is set on honoring him.