A popular though possibly misguided usage of this verse is as evidence that Satan began his career as an angel who, because of his prideful challenge to God's sovereignty, was thrown out of heaven. Jesus may have alluded to the writings of Isaiah when he said, I saw Satan fall like lightning from heaven (Luke 10:18); language which should probably be taken more figuratively than literally. Both the king of Babylon (though Babylon did not yet exist at the time of Isaiah ben Amoz) and Satan ruled powerful empires and were seemingly invincible.
Yet Isaiah says the ruler of Babylon, domineering as he may be, is subject to the power of God. In fact, chapters 13-23 are Isaiah's oracles against the nations (which have parallels in Jeremiah, Ezekiel, Amos, Zephaniah and Zechariah), which testify that all nations and powers are subject to Yahweh, as is Satan and his kingdom.
If we don't see it now, one day we will: Is this the man who shook the earth and made kingdoms tremble? (v. 16) No matter what the threat, one day we will look back and say, I was afraid of that? God really is faithful.
Enemies only look invincible when we look ahead, not when we look back.
As you look ahead to the coming weeks, what threat feels overwhelming?