In Revelation 17:6 the whore John has described in 17:1–5, “Babylon the great, mother of prostitutes and of earth’s abominations,” is described as “drunk with the blood of the saints, the blood of the martyrs of Jesus.”
The fact that she’s drunk with the blood of the saints means that the wicked world has been killing Christians. Why do Christians get martyred? How does it happen?
These are the enemies of God who are troubling God’s people: governments that put Christians to death or imprison them; social networks and dynamics among groups of people that build a plausibility structure in which the truth of the Bible is regarded as backwards and shallow and for the weak; and these are powers at work in the world to make Christianity seem negative or weak or foolish or not respectable (Revelation, 327).
That’s probably not a very good translation of Revelation 17:6. “Martyrs” ought be translated as “witnesses.” Translating it as “martyrs” is anachronistic. A few generations later that passage helped create the current definition of “martyr.” There’s no evidence that the word meant dying for the faith in John’s day. John, I believe, is speaking more broadly of the entire witnessing community, which will suffer persecution. “Saints” in the passage should be read as encompassing the entire community of believers.