There are also passages in which John refers to martyrs. Revelation 6:9-11 and 20:4 seem to indicate that many Christians were tortured and killed for their beliefs, and, in his vision, they "…cried out with a loud voice, 'Sovereign Lord…how long will it be before you judge and avenge our blood on the inhabitants of the earth?'" (6:10 NRSV). John portrays the Roman Empire—called "the great whore Babylon"—as "being drunk with the blood of the saints and the blood of the witnesses to Jesus" (17:6 NRSV). The Book of Revelation progresses with the wrath of God poured upon the Earth as retribution for the sufferings of the faithful Christians. It ends with the Fall of Babylon and Christ's defeat of Satan, after which there is "new heaven and a new earth" (21:1 NRSV).