We know from earlier that the foreheads of 144k have been sealed. Now we see that those 144k are spared from this terrible plague. What about the Gentile Church? It is for this reason and more that many believe that the Church has left the storyline completely having been raptured (they have not specifically been mentioned since chapter 3), they are a part of the numerous host surrounding the throne. There may be new tribulation believers haven seen these occurrences first hand of course.
The end of the world is often thought of as men inflicting evil upon men, mankind out of hand. What we are seeing here however are things totally outside the scope of man's doing. Stars falling and rivers contaminated by the fall out, pits being opened up, Grasshopper like scorpions stinging with five month agonies, one third of this and that and of man. Even this is not enough to change the hearts of many as if they blame God for allowing this to happen.
The question becomes where are we chronologically in the time-line? Early, mid, late? We are not sure. Revelation does not seem to be written in strict chronological order. Remember also the prophecies of the other end time prophets. Chronology may not be as important as motion, other passages may be running concurrently with this and it be too confusing seeing through too wide a lens. If we come to understand the general motion with these particular details, when these chronological times are revisited with other/further context/details we are more likely to connect them.
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