Because they are in heaven – the place of peace, purity and prospect, they engage in praise. What do they say in their song?
The first detail to observe is that the same battle is fought during the Old and New Testaments. The battle is between the kingdom of God and the kingdom of darkness. Israel had the truth, Egypt was built on a system of lies. In heaven, believers from both campaigns share the victory song.
The song celebrates the sovereignty of God. His sovereignty extends to the nations and to all his actions in those nations – he is ‘King of the nations’ who exhibits almighty power. His actions are wonders because they reveal his wisdom and power and consistent adherence to truth as well as his constant ability to defeat whatever the hostile nations bring against him.
Moreover, the song stresses the singularity of God. There is none like him and it is impossible for anyone to opt out of glorifying him in the end. For many, their glorification will not be saving, because they will acknowledge his uniqueness reluctantly. The biblical way of saying that God is unique is to refer to his holiness. Holiness is a comprehensive word because it combines everything that makes up perfection. Adam was holy when he was first created. Because the holiness here is divine perfection, it is inevitably elevated above everything else, as we see in the vision described in Isaiah 6. This is a reason why we should not sin because every sin is the opposite of the holiness of God.
The fourth feature of the song is that it rejoices in success. Worshippers of God will come from all the nations after they hear about his righteous acts. Although not specified here, the righteous acts are the ones we include in the gospel. So John, and us, are prepared for looking at the seven plagues by being reminded of the redeemed in heaven. They will have been gathered in during the days of the plagues.