Habakkuk 3:12 (ESV)

12 You marched through the earth in fury; you threshed the nations in anger.

God comes in awesome power to judge the wicked Babylonians with his wrath. His coming is like an army marching into battle. He is furious with them and moves through the earth to show that he will deal decisively in his judgment upon them. His anger is expressed as that of threshing the nations. This was the process in which the wheat was separated from the chaff on the threshing floor. His action against the Babylonians would result in them being thoroughly defeated and his people being released from their oppression against them.