What is to follow on earth now begins, when the seals are opened. It will be remarked here, that John, standing in the ruin of the assembly, gives prophetically all that passes from that failure till Christ comes in chapter 19. There is no ascension no rapture, save as far as chapter 12 gives both together.
The first seals are simple; nor have I anything to offer very new upon them: first, imperial conquests then wars, then famine, then pestilence, carrying with it what Ezekiel calls God's four sore plagues (sword, famine, pestilence, and the beasts of the earth). They speak of the providential course of God's dealings, and hence the four beasts call attention to it; but they have God's voice in them, the voice of the Almighty: that, the ear of him who has the Spirit hears. These complete providential plagues, as spoken of in scripture. Then direct judgments follow; but these are what we may call preparatory measures.
I have to notice that in the full plagues of verse 8 the whole Roman earth is not included. It is a fourth, not a third. The plagues too, note, are limited in extent of sphere, not universal.
The saints are those whom God is really thinking of, and they come in remembrance before other scenes are brought out. Those who had been martyred for the word of God and their testimony demand how long before they were avenged; for we have ever to do here with a God of judgment. Their being under the altar means simply that they had offered their bodies, as sacrifices for the truth, to God. The white robes are the witness of their righteousness---God's declared approval of them; but the time for their being avenged was not yet. I do not think giving white robes is resurrection. The first resurrection is sovereign grace, giving us the same place with Christ ("for ever with the Lord "), consequent on His work and His being our righteousness, which is alike to all of us. White robes thus conferred are the recognition of the righteousness ('dikaioomata")  of the saints-hence are seen in chapter 19 at His appearing. "They shall walk with me in white, for they are worthy." I am not denying that we are made clean, and our robes white in the blood of the Lamb. But, even where this is said in chapter 7, I think it refers especially to the way they have been associated by faith with the suffering position of Christ. Here white robes are given them-their service owned; but, for avenging, they must wait till a new scene of persecution had brought them companions who had to be honoured and avenged like them. Still this marks progress, and finds its causein the dealing of God to bring about this new state of things, which issues in final judgment and setting aside of evil. Here the judgments are providential.
The next thing to the claim for avenging is the breaking up of the whole system of earthly government, and the terror of all on earth. How clearly we see here that we are in a scene of judgment, and that God is a God of judgment! The desires of the saints are like the desires of the Psalms. We are not with children before the Father, with grace, with the gospel, and the assembly; but with Jehovah, where God is a God of judgment, and by Him actions are weighed. We are on Old Testament ground, that is, prophecy, not grace to the wicked, though judgment brings in blessing.
The opening of the sixth seal brings an earthquake, that is, a violent convulsion of the whole structure of society. All the governing powers are therein visited; and, seeing all subverted, small and great think (with bad consciences as they have) that the day of the Lamb's wrath is come. But it is not, though preparatory judgments with a view to His kingdom are there. But God thinks too of His saints on earth (where we must remember, the assembly is never now seen) before the scenes which follow, whether judgments on the Roman earth or the special workings of evil, to secure and seal them for that day.