Revelation 12 in chronological order:
Israel gives rise to the messiah; Jesus then ascends to heaven
Revelation 12:1-5 And a great sign appeared in heaven: a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars.
2She was pregnant and was crying out in birth pains and the agony of giving birth. 3And another sign appeared in heaven: behold, a great red dragon, with seven heads and ten horns, and on his heads seven diadems.
4His tail swept down a third of the stars of heaven and cast them to the earth. And the dragon stood before the woman who was about to give birth, so that when she bore her child he might devour it.
5She gave birth to a male child, one who is to rulea all the nations with a rod of iron, but her child was caught up to God and to his throne,
After Jesus is caught up to God and to his throne, receives his kingdom, and is given authority, Satan is thrown down out of heaven. The dragon then pursues the woman (Israel)
Revelation 12:7-13
7Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back,
8but he was defeated, and there was no longer any place for them in heaven.
9And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world—he was thrown down to the earth, and his angels were thrown down with him.
10And I heard a loud voice in heaven, saying,
“Now the salvation and the power and the kingdom of our God and the authority of his Christ have come, for the accuser of our brothersb has been thrown down, who accuses them day and night before our God. 11And they have conquered him by the blood of the Lamb and by the word of their testimony, for they loved not their lives even unto death.
12Therefore, rejoice, O heavens and you who dwell in them! But woe to you, O earth and sea, for the devil has come down to you in great wrath, because he knows that his time is short!”
13And when the dragon saw that he had been thrown down to the earth, he pursued the woman who had given birth to the male child.
Israel is nourished for 3.5 years after Christ is caught up to God. Satan, furious of this, goes off to make war with Israel's offspring.
Revelation 12:6,14-17
and the woman fled into the wilderness, where she has a place prepared by God, in which she is to be nourished for 1,260 days. But the woman was given the two wings of the great eagle so that she might fly from the serpent into the wilderness, to the place where she is to be nourished for a time, and times, and half a time. 15The serpent poured water like a river out of his mouth after the woman, to sweep her away with a flood.
16But the earth came to the help of the woman, and the earth opened its mouth and swallowed the river that the dragon had poured from his mouth.
17Then the dragon became furious with the woman and went off to make war on the rest of her offspring, on those who keep the commandments of God and hold to the testimony of Jesus.
What is the significance of this 3.5 years?
