Expositor's Bible Commentary Commentary Revelation 16:7

"And I heard the altar saying, Yea, O Lord God, the Almighty, true and righteous are thy judgments." — Revelation 16:7 (ASV)

Here the reference to blood calls forth the dialogue between the angel and the altar concerning the logic of the plagues. The blood that sinners drink is just requital for their shedding of the blood of the saints (15:1–4) and prophets (11:3–13; cf. 17:6; 18:20). With blood, God vindicates the blood of the martyrs of Jesus. People must choose whether to drink the blood of saints or to wear robes dipped in the blood of the Lamb.