And I heard another voice from heaven, saying, Come out of her, my people... Since the Church will have just been taken up to be with the Lord, this must be talking about the remnant of Israel. This would agree with the rest of this statement: ...that ye be not partakers of her sins, and that ye receive not of her plagues.

5 For her sins have reached unto heaven, and God hath remembered her iniquities.

End-time Babylon the Great will be the anti-type of Sodom and Gomorrah (See Gen. 18:20-21.)

6 Reward her even as she rewarded you, and double unto her double according to her works: in the cup which she hath
filled fill to her double.

Reward her even as she rewarded you... Through the use of the media, Israel, and the Western World, have shown their determination not to let the world forget about the atrocities against Israel during the Second World War.
...and double unto her double according to her works... Does this verse mean that the world system will have doubled its efforts to destroy the Israelites and in return, the Jews will get to do unto them double what they were trying to do to them? Or does this mean that Babylon the Great's treatment of Israel will have been duly noted by God and that it will pay in double for its treatment of Israel? and that, somehow, Israel will play a part in how spiritual Babylon the Great will be repaid? ...in the cup which she hath filled fill to her double. Could this "double" be indicating that this behavior will take place during "both" halves of Daniel's 70th Week?

7 How much she hath glorified herself, and lived deliciously, so much torment and sorrow give her: for she saith in her
heart, I sit a queen, and am no widow, and shall see no sorrow.

Already, the Judeo/Christian ethics that made the free world great have been trashed for the "dog eat dog" mentality that will bring this judgment upon the world system. Loving your neighbor as your self and doing good to your enemies have been replaced by the delusions of grandeur, the getting rich at the expense of others, the mindset that no one will have to pay for the grief they cause others, and the mirage that life will go on forever just like it is. A world system that hoarded its billions and ignored the starvation and sicknesses of its neighboring third world countries, will get a taste of the misery they ignored or held in contempt.

8 Therefore shall her plagues come in one day, death, and mourning, and famine; and she shall be utterly burned with fire: for strong is the Lord God who judgeth her.

Therefore shall her plagues come in one day, death, and mourning, and famine; and she shall be utterly burned with fire... It is the way of our gracious Father to have longsuffering with the man that He made in His image; and God has endured the world system / spiritual Babylon the Great while He has been seeking to save the lost. However, there will come a day when His longsuffering will come to an end.

...for strong is the Lord God who judgeth her. God is omnipotent; i.e., all power is His. (Even the power that Satan has had with which to try the hearts of man was given to him by God; and after Satan's task is finished, God will remove his power and confine him to the Lake of Fire for an eternity of torment with those that he has deceived.)

9 And the kings of the earth, who have committed fornication and lived deliciously with her, shall bewail her, and lament for her, when they shall see the smoke of her burning,

To see the great cities with their sky scrappers and their lush, leisure way of life all going up in smoke will be terrifying and grievous to bear. Sadly, though, instead of spiritual Babylon's demise stricking fear in the heart of man, their first emotion will be of sadness and sorrow for Babylon's destruction; and their first concern will be for the loss of their wealth, not the lives of their families and their neighbors!

10 Standing afar off for the fear of her torment, saying, Alas, alas that great city Babylon, that mighty city! for in one hour is thy judgment come.

Although Babylon the Great is generally thought of by theologians to be the spiritual powers behind the system that runs this world, this verse talks about Babylon as if she is an actual city — or at least, something physical whose judgment can be seen. Will the inhabitants of the earth have their delusion lifted long enough to realize that the Bible was the Word of God? and that Satan is a real being who has been duping mankind for centuries? and that they are witnessing the hour of his judgment??? Whatever the case, the sight will be so dreadful that they will "fear" and attempt to distance themselves; and part of this fear might very well be the settling in of the realization that their judgment is caught up in the judgment of the great city — that their hour of judgment is also come!

11 And the merchants of the earth shall weep and mourn over her; for no man buyeth their merchandise any more:

12 The merchandise of gold, and silver, and precious stones, and of pearls, and fine linen, and purple, and silk, and scarlet, and all thine wood, and all manner vessels of ivory, and all manner vessels of most precious wood, and of brass, and iron, and marble,
13 And cinnamon, and odours, and ointments, and frankincense, and wine, and oil, and fine flour, and wheat, and beasts, and sheep, and horses, and chariots, and slaves, and souls of men.
14 And the fruits that thy soul lusted after are departed from thee, and all things which were dainty and goodly are departed from thee, and thou shalt find them no more at all.

15 The merchants of these things, which were made rich by her, shall stand afar off for the fear of her torment, weeping and wailing,

Again, we see the people who were used by Satan to build mysterious Babylon the Great being aware that the judgment of God is upon their creation, and again we see them trying to distance themselves from the system?/city? that had made them rich.

As with the first half of this set, the people will not have their priorities right. Instead of weeping and wailing for the plight of their souls and their families and friends, they will be mourning the loss of their wealth.

For in one hour so great riches is come to nought. As with the first half of this set, all of this will come about during "one hour."

... And every shipmaster, and all the company in ships, and sailors, and as many as trade by sea, stood afar off, Like the merchants, the shipping industries will be trying to distance themselves from this "sinking ship."

Also, as with the merchants, the shipping industries will be mourning the source of their wealth. We're not given any indication that they will experience personal grief or repentance.

And they cast dust on their heads, and cried, weeping and wailing... Casting dust on one's head before God is a Hebrew custom indicating humility and trust. Click here for a brief overview of "dust" in the Bible. However, in this instance, it is the "citizens" of "Babylon" who will be casting dust on their heads. Does this indicate that they will be "carefully seeking a place to repent" (Cf. Heb. 12:16-17.) or does it mean that they will have Hebrew blood on their heads? Because we're only given that the people will be weeping and wailing for the city that made them wealthy, we can probably assume that the dust on their head does not indicate godly sorrow and repentance.

saying, Alas, alas that great city, wherein were made rich all that had ships in the sea by reason of her costliness! for in one hour is she made desolate. This indicates more lamenting; also, we are given again to understand that Babylon the Great's demise will come suddenly — i.e., in one "hour."

Vine's Expository Dictionary
hour: ...Latin, hora, Eng., "hour," primarily denoted any time or period, especially a season.
Easton's Bible Dictionary
hour: ...used in the New Testament frequently to denote some determinate season (Matt. 8:13; Luke 12:39).--

This brings to mind the Scripture: "Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord (Rom. 12:19). As with the Jews of the first half of this set, God will avenge those who have been mistreated by the ungodly in the world. However, this time, the angels of heaven, the Church (represented by the "holy apostles"), and the Jews (represented by the "prophets) will rejoice because those who put their faith in God will have finally been avenged.

(By the way, Jesus Himself gave us the reason that the world would hate the believers.

John 15:19
If ye were of the world, the world would love his own: but because ye are not of the world, but I have chosen you out of the world, therefore the world hateth you. John 17:14
I have given them thy word; and the world hath hated them, because they are not of the world, even as I am not of the world.)

And a mighty angel took up a stone... This analogy would make sense to John. He understood that Christ Jesus was the true "stone" that the builders had rejected. And he understood that the beast would be trying to counterfeit Christ.
...like a great millstone... Also, in his day (as in Old Testament times), each family had a pair of millstones (the "nether" [the lower stone] and the "upper" stone) with which to grind up their seed into meal and flour. (Note that for reproductive use, the "ground" seed is useless. Similarly, the Word of God — the seed of the Kingdom of God — has to be intact and faithfully spread to do the work of God. For our understanding of the millstone of prophecy, CLICK HERE.) Undoubtedly, Satan's version of "the Word" will be so mangled that it will have little if any resemblance to the Bible. Consequently, we could say that this "stone" that the angel cast into the sea stands for the devil being cast to the earth as per Rev. 12:12; and that the "great millstone" is the religious organization under the control of the beast.

...and cast it into the sea, saying, Thus with violence shall that great city Babylon be thrown down, and shall be found no more at all. As we've said repeatedly, in prophecy, the sea is the mass of people without a covenant with God. However, in this particular verse it seems as though the sea and the great city of Babylon are treated as being synonymous. Of course, Babylon the Great will be found no more because it will go up in flames with the rest of the world according to II Pe 3:10.

But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be
burned up.

This first list of things that will be no more includes the gifts that were given to Jubal (The gift of music) and his brother Tubalcain (The gift of working with metal — Genesis 4:21-22) — as well as the gifts of all crafts. Also, the millstone here probably represents manufacturing of foods, its original purpose being the grinding of meals and flours for cooking purposes.

And the light of a candle shall shine no more at all in thee... This could be referring to the fact that there will be no more "church" (called-out-ones) in her midst, but it could also be a very poetic way of saying that there will be no more human life.

Pro 20:27 The spirit of man is the candle of the LORD, searching all the inward parts of the belly.
Pro 24:20 For there shall be no reward to the evil man; the candle of the wicked shall be put out.
cf.
Ec. 12:7 Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it.

...and the voice of the bridegroom and of the bride shall be heard no more at all in thee... No more will man have opportunity to hear the witness of the believer and the wooing of the Holy Spirit; for there will be no more earth and no more seed of Adam to walk upon it.

...for thy merchants were the great men of the earth... This is self - explanatory: i.e., the men wanted to be "great" to one another instead of "great" in faith toward God. Consequently, they were open to lying spirits.

...for by thy sorceries were all nations deceived. Remember, spiritual Babylon the Great will be a very religious rule, a "counterfeir theocracy" if you will.

24 And in her was found the blood of prophets, and of saints, and of all that were slain upon the earth

More explanation of why Babylon the great and the earth that she had corrupted will be destroyed.