In Revelation 15 we are introduced to 7 angels who have the 7 last plagues. Verse 1 says “in them the wrath of God is complete”. Later, one we see 7 angels who are given 7 golden bowls full of the wrath of God that will be poured out on the earth.
In 2-4 we see another scene of worship in heaven (2-4). The worshipers are those who were victorious over the beasts, his image, his mark, and the number of his name, and they are singing the song of Moses and the Lamb. The songs seem to highlight the power and justice of God – “Great and marvelous are Your works”, “just and true are Your ways” – important considerations in light of the judgments taking place.
Main point: the stage is all set for the outpouring of the 7 bowls of wrath. It says these will complete the wrath of God.
Those pictured as praising God in 2-4 are described as victorious over the beast, yet they might have given their life for their faith. In what sense would that be a victory?
Note: The song of Moses refers to Exodus 15 and a song Moses sang to the children of Israel after crossing the Red Sea. How might that event be similar to what has happened he in Revelation 15?