What does Revelation 19:21 mean?
The armies that followed the beast in his battle against Christ meet a fatal end. The sword from Christ's mouth slays them. Since the sword represents the Word of the Lord, it is safe to say that just a word from our Lord is sufficient to snuff out the lives of the beast's numerous soldiers. The "sword" has two edges (Revelation 1:16). It can save those who choose to believe in Jesus as Savior or condemn those who reject Him (Hebrews 4:12). The number of the slain soldiers is so numerous that all the vultures that are called to "the great supper of God" (Revelation 19:17) gorge themselves on the dead bodies. Of course, the slain soldiers experience not only physical death but also eternal death, as Revelation 20:11–15 explains.Belief in the existence of hell and eternal suffering is unpopular with certain religious teachers. They would rather believe that everyone goes to heaven eventually, or they choose to believe in the annihilation of the wicked. However, the Bible is clear; hell is real and those who go to that dreadful place experience real suffering forever. The first to experience that torment, even before the millennial kingdom, are the Antichrist and the False Prophet (Revelation 19:19–20).
This victory sets up Christ's thousand-year reign on earth, described in chapter 20.