Then I saw in the right hand of him who was seated on the throne a scroll written within and on the back, sealed with seven seals. And I saw a strong angel proclaiming with a loud voice, “Who is worthy to open the scroll and break its seals?” (Revelation 5:1-2, ESV)
God has written before the foundation of the world, a scroll. The scroll described here is reminiscent of important Roman legal documents, which were scrolls sealed with seven wax seals. Often these were last wills and testaments. This looks to be God's redemptive plan of history, seeing what happens as the seals are broken and finally when John later eats the scroll.
Who is worthy to open the scroll? No one is worthy except Christ Jesus.
God not only rules in heaven with great power and authority, but God has ordained all that will happen in history. All of this will be consummated to at the last judgment and when the new heavens and earth are ushered in.
We are not to be disheartened in trials and trouble. God rules and God has planned all that will come to pass.
We now stand poised to see history unfold in Revelation. The history will come in cycles of retelling. The history from Christ's first coming to the final judgment will in several series, when the seals are broken, and repeated again when the trumpets are sounded, and yet again in other ways. This retelling of history over and over will give us different vantage points to see what is going on and see the deeper spiritual battle that takes place. Think of these retellings, these recapitulations of history, as overlays on the time span from Christ's first coming to his second coming. Each overlay provides more understandings of how God is at work in defeating evil.
God reigns in heaven. God reigns in righteous anger, purity, grace and mercy. God reigns in that he has planned all the has happened and will happen in history -- to his glory and to the victorious