Chapter twelve begins with these words:
"A great and wondrous sign appeared in heaven..."
Obviously John was pretty impressed with what he saw at this point. And what he saw was "a woman clothed with the sun, with the moon under her feet and a crown of twelve stars on her head. She was pregnant..."
Bible scholars pretty much agree that this "woman" represents the Jews. What they don't agree on is whether or not this portion of John's book is prophecy of things to come or retelling things that have already happened. I personally believe John has been given a glimpse into past things that happened in heaven and on earth. Things that John and the other believers may not have had a real grasp on. Remember that in chapter 1, verse 11 John is told to "write on a scroll what you see and send it to the seven churches...".
Some things to consider:
1. If the woman represents the Jews, then the male child she gives birth to (v. 5) could certainly be Jesus. That had already happened by the time John wrote this book.
2. The dragon, who is named as Satan in verse 9, tries to devour the baby but isn't successful. Again, that is true and had already happened. Satan did not win when Jesus was crucified. Instead, Jesus defeated death and gave us salvation through his blood!
3. Verse 7 describes a war in heaven where Michael and his angel army defeat the dragon, Satan, and his angels. They lose their place in heaven and are hurled to the earth. My personal belief is this event happened way back at the beginning of time.
4. Once Satan realizes he's lost his place in heaven, he begins to persecute the woman--the Jews(v. 13)--and her offspring--which is us (v. 17). Why do I say we are the offspring? Because we who believe in Jesus Christ have basically been adopted into God's chosen people, the Jews. Verse 17 describes the woman's offspring as "those who obey God's commandments and hold to the testimony of Jesus."
Something interesting to meditate on is found in verse 10.
"For the accuser of our brothers, who accuses them before our God day and night, has been hurled down."
John makes it clear that Satan is always, always, always accusing us. Trying to make us look bad in the sight of God. Can't you just see it? Can't you just hear him while he stands before the throne, pointing his finger at you, saying, "God, look what that person has done! Look at the sins they've committed. Surely you should punish them!"
But thankfully verse 11 reminds us that God is willing to forgive us.
"They [believers in Jesus Christ] overcame him [Satan] by the blood of the Lamb and by the word of their testimony; they did not love their lives so much as to shrink from death."
I'll leave you with the last words in verse 12, because all you have to do is open your eyes to all that goes on in the world and see that it is true right now!
"But woe to the earth and the sea, because the devil has gone down to you! He is filled with fury, because he knows that his time is short."