In the right hand of God Almighty on the throne, is a scroll “written inside and out” sealed and closed with seven seals. As the book was written all over and already sealed, that means you and I don’t get to speculate on its content. It is finished and complete. So much for the notion of continuous revelation and visions. As the contents of the book have been set, the action therefore cannot be fulfilled until the seals are removed.
The seals of the scroll are progressively broken, which is reported in chapters 6 through 11, and at that time the content of the whole would be fully made known (see 11:15). Obviously, the contents are indicative of what was to “shortly come to pass.”
Only the Christ – The Anointed One, The Lion of Judah, and soon identified as “a Lamb as if it had been slain” is worthy (authorized) to break the seals and to begin the unfolding of the purpose of God. All seven of the seals are under his control. Therefore, it follows, all power and authority in the realms of men has been granted to the Lamb of God.
In chapter 10:4-7, when the seventh seal is broken and the seven thunders sound “…the mystery of God would be finished.” In chapter 11:15 when the seventh angel has sounded the scroll contents would be completed and fully revealed.
We are told that this is the avenging of the blood of those who died “for the word of God and the testimony which they held.”
During this time, John was informed that the only one who is worthy to remove the seals is the Lion of Judah (See Genesis 49:9, 10 for the blessing of Judah by Israel). The Lion of Judah is the same that is called the “Root of David” elsewhere (in Isaiah 9:1 and 10). The Lion symbolizes the Messiah in OT prophecy. So, there can be no dispute as to who that is.
When John looks, he does not see a Lion but, as noted, a “lamb as if it had been slain.” He sees the “Lamb of God,” (as John the Baptizer had said), the Chosen one of Israel, the Messiah – the Christ resurrected: which is the same as the mentioned Lion of Judah – the final atoning sacrifice.
The Lamb takes the scroll from the hand of God to begin to break the seals and to reveal the purpose of God. He is worthy because he has fulfilled everything and had been slain and raised for all mankind to usher in the new covenant of righteousness.