In the Greek the word “marvel” is placed at the head of the sentence so as to stress it. John was not to “marvel” (in its negative sense: be dismayed
) for reasons the angel has already hinted at. Certain earthlings, in contrast, will “marvel” (in its positive sense: be impressed
) upon seeing the beast. The explanation John gives is, “Because it was and is not and is to come.” It should further be noted that in the antithesis God announced in Genesis 3:15, those whose names are not written in the book of life are on the side of the dragon (and hence the beast) in opposition to the Lord God. That explains their “marveling” (being impressed).
8 The beast that you saw was, and is not, and is about to rise from the bottomless pit and go to destruction. And the dwellers on earth whose names have not been written in the book of life from the foundation of the world will marvel to see the beast, because it was and is not and is to come.