John heard praise of God in heaven that interrupted his narration of the outpouring of the bowls of wrath briefly.
16:5 The "angel of the waters"evidently refers to the angel responsible for the sea and fresh water, the superintendent of God's water department. Scripture reveals that angels affect the elemental forces of nature (cf. Ps. 104:4; Heb. 1:7; Rev. 7:1; 9:11; 14:18). This angel attributes righteousness to the eternal God for judging in kind (cf. 15:3-4; Gal. 6:7). The holy and righteous God can judge humanity according to the lex talionisprinciple because He is eternal.
16:6 Specifically, God poured out blood on the earth-dwellers because they poured out the blood of His saints and prophets. He makes the punishment fit the crime (cf. Isa. 49:26).
"Pharoah tried to drown the Jewish boy babies, but it was his own army that eventually drowned in the Red Sea [Exod. 1:22; 14:28]. Haman planned to hang Mordecai on the gallows and to exterminate the Jews; but he himself was hanged on the gallows, and his family was exterminated (Es. 7:10; 9:10). King Saul refused to obey God and slay the Amalekites, so he was slain by an Amalekite (2 Sam. 1:1-6)."514
The saints refer to all believers, and the prophets are those who delivered messages from God to humankind (cf. 11:18; 18:24). The angel affirmed that those guilty of slaying the saints and prophets deserve what they get. They took lives contrary to God's will, and now God is taking their lives in exchange.
16:7 The Tribulation martyrs offer their "amen"from under the altar (6:9; 15:3-4). The altar was the personification of those associated with it earlier in John's vision (cf. 9:13; Gen. 4:10; Luke 19:40; Heb. 12:24). God always judges consistently with His character, which these martyrs describe as being almighty, true, and righteous.
