1Then I heard a loud voice from the temple, saying to the seven angels, "Go and pour out on the earth the seven bowls of the wrath of God."
Rev_16:1 "Then I heard a loud voice from the temple, saying to the seven angels"Rev_15:8 shows that this must be the voice of God Himself. This last group of angels had ultimate authority to destroy God's earth. In the OT the death angel and the angel of destruction are God's servants, not Satan's.
▣"Go and pour out on the earth the seven bowls of the wrath of God" This is an OT symbol for the judgment of God on unbelieving nations (cf. Psa_79:6; Jer_10:25; Eze_22:31; Zep_3:8). This term is used often in this context for God's wrath on unbelievers (see note at Rev_7:14, cf. Rev_16:1-4; Rev_16:8; Rev_16:10; Rev_16:12; Rev_16:17) because of
1. their blasphemy (cf. Rev_16:9)
2. their persecution of believers (cf. Rev_16:6)
3. their stubborn refusal to repent (cf. Rev_9:20-21; Rev_16:9-12)