^15:3And they sang the song of Moses the bond-servant of God and the song of the Lamb, saying,

"Great and marvelous are Thy works,
O Lord God, the Almighty;
Righteous and true are Thy ways,
Thou King of the nations.

And they SANG

This is the "Praise and Worship" time before the temple is opened (verse 5) for a very different "passing out the bowls" service.

1. the song of Moses the bond-servant of God and

   It does not matter which of the two Old Testament songs of Moses (Exodus 15 or Deuteronomy 32) this song is patterned after. The theme is of victory after very difficult times.

   This part of the song is specifically Jewish in context and meaning (see the "Thy Works" comments below).

2. the song of the LAMB, saying,

   This really is only one song, a merged version of the song of Moses and the song of the Lamb. And I suspect this is only a snippet of the whole song. The result of this song is given in Daniel 7:13-14 where we see the LAMB's victory and the resulting dominion accrued to Him.

   • GREAT and MARVELOUS are Thy WORKS, O Lord God, the Almighty;

     This is really a continuation of the thanksgiving begun in Revelation 11:17 since we again see the fullest and most complete title for God used there also.

     "Thy Works" can be both physical and spiritual. That is, this part more closely aligns with the Song of Moses. Moses saw GREAT and MARVELOUS WORKS:

     • Deliverance from Egypt (Exodus 14)
     • The Ark (Exodus 25:10-22)
     • The Two Tablets of Stone with the Ten Commandments (Exodus 34:29-35)
     • The Tabernacle (Exodus 40:16, 34-38)

   • RIGHTEOUS and TRUE are Thy WAYS, Thou King of the nations.

     "Thy Ways" are spiritual attributes, RIGHTEOUS and TRUE. Both of these attributes belong to Christ, the LAMB (John 1:17, John 14:5-11, Matthew 25:31-46). The King of the nations had been claimed by the beast (at least he thought so) - Revelation 13:7.

     The singers here went through the first half of the Tribulation (similar to crossing the Red Sea) without taking the mark of the beast. They counted on the TRUTH and the RIGHTEOUSNESS of the King of the nations. And they were RIGHT!

This verse is the first part of the song. The second part follows in the next verse. Check out the parallel song in Jeremiah 10:6-7-10.