John has seen the "great sign" of the woman (12:1), the "sign" of the "great" red dragon (12:3). Now he sees the "great and marvelous" sign of the seven angels with seven plagues (also called the seven bowl judgments) in which God's wrath will be complete (15:1). These plagues (and the third woe) do not really begin until Revelation 16.
In the interim, there is this wonderful scene in heaven with a sea of glass (4:6) mixed with fire (representing wrath and judgment) and the tabernacle (Exodus 40:34, 35) filled with the smoke of the glory of God and from His power. Those "victorious over the beast" were those who refused the mark ("the number of his name"). They "overcame him because of the blood of the Lamb and because of the word of their testimony, and they did not love their life even when faced with death" (12:11 - one of my favorite verses!).
The "song of Moses" and "song of the Lamb" tie the Old Testament and New Testament together! You might recall that the "Song of Moses" was a song of praise when God delivered the Israelites from bondage to the Egyptian pharaoh after they crossed the sea on dry land (Exodus 15). The "song of the Lamb" is a song of praise for the ultimate deliverance from Satan's power (also sung by the sea)!
This song and the tying together of the Old and New Testament is punctuated by a quote from Psalm 86:9, "All nations (ethne) will come and worship before you." Remember that this is what I have been saying from the beginning of the Bible Book Club, God has intended for ALL PEOPLES GROUPS to worship Him.
I honestly have had chills running up and down my spine as I have meditated on Revelation 15 for two days. So beautiful. So worshipful to God. I pray You can see the beauty of this chapter too.
APPLICATION in PRAYER
Take time to pray through the song of Moses and the song of the Lamb today:
Great and marvelous are Your works,
O Lord God, the Almighty;
Righteous and true are Your ways,
King of the nations!
Who will not fear, O Lord, and glorify Your name?
For You alone are holy;
For all the nations will come and worship before You,
For Your righteous acts have been revealed.