Revelation 5:2

And I saw a strong angel proclaiming with a great voice, Who is worthy to open the book, and to loose the seals thereof?

Who is worthy ... The key for unlocking the mystery written in the scroll was not power only, but morality, righteousness, holiness, and justice - in a word, worthiness. The great problem to be solved in human redemption was simply this: how could God injustice do it? Paul stated it thus: "That he might be just and the justifier of him that is of the faith of Jesus" (Romans 3:26).

Inherent in this interpretation is the fact that the vision at this point is retrospective in time, looking to the period when the salvation of Adam's race appeared to be absolutely impossible. As Caird said, "Some of the contents (of the scroll) are already past."[11]

The situation in this verse appears to be almost identical with that described in Psalms 40:6-8, in which Christ, in his pre-existent state before the Incarnation, responded to the challenge of redeeming mankind in the words:

Then said I, Lo, I come (In the roll of the book it is written of me) To do thy will, O God.

This is the remarkable passage in which the preexistent Christ spoke of "the body" God had prepared for him. For fuller comment on that remarkable passage, see my Commentary on Hebrews, p. 213.