Revelation 5:9

The Lamb’s receiving authority from God to advance God’s plan of the ages led these 28 angels to sing a new (Gr. kainen, lit. fresh, distinctive in quality, rather than recent) song of praise. It may be new in the sense that it celebrates His death that inaugurated a new covenant. [Note: Mounce, p. 147.] However, I think it was probably new in the sense that it represented new praise for a new deliverance about to take place.

"This [i.e., "a new song"] is a well-known expression in the psalms, relating to songs sung on festal occasions and celebrating new mercies from God, especially his deliverances from distress (e.g., Psalms 40:1; Psalms 98:1). It receives a deeper meaning in Isaiah 42:10, where the new song relates to the new and greater deliverance which the Lord is about to make in the earth." [Note: Beasley-Murray, pp. 126-27. Cf. Psalms 33:3; 40:3; 96.1" class="scriptRef">96:1; 149:1, 9.]

In this song the Lamb receives honor as being worthy in view of four things. The first is His death. The second is the purchase (redemption) of a people for God by His death, including those yet to be saved (cf. Revelation 14:2-3; Revelation 15:2-4). People from every branch of the human family will make up this company (cf. Genesis 10:5; Genesis 10:20; Genesis 10:31). This does not mean that all will be saved because Jesus died for all, of course. Only those who appropriate the benefits of Christ’s death by faith will be. Tribes, tongues, peoples, and nations represent divisions of humanity based on lineage, language, race, and political orientation. Together these terms describe the universal nature of the redeemed people of God.