Remember, in these 7 visions the Resurrected Church is seeing "Judgement Day" from their perspective in heaven.

In these verses, it becomes clear to them that Judgement Day began with the crucifixion and resurrection of Christ.

Vs. 7-9: the battle is between Michael with his angelic armies and Satan with his. Satan loses and is cast out of heaven, to live on earth.

Note: Our culture is so familiar with Paradise lost that we think the story Milton tells of the fall of Satan and his angels is the story that Scripture tells. So most of us think that Satan was once a beautiful angel who became jealous of God and rebelled. As punishment, he and his followers were thrown out of heaven even before the creation of the world.

This is an interesting story - BUT IT IS NOT SCRIPTURAL.

Here in Rev 12:7-12 we hear the story told in Scripture of how Satan is cast out of heaven. The story told here doesn't explain much about why Satan could tempt Jesus during his earthly ministry and not be thrown out of heaven. This story doesn't explain a whole lot of the questions you will now have -- which is why Milton gives answers in Paradise Lost. But Milton is only Milton - and Scripture (with all its loose ends and unanswered questions) is CANON.

We find Satan in heaven up until this point because according to Scripture, up until now, he has every right to be there.

In Hebrew, the word "satan" means "adversary". Satan is the prosecutor in the law court of God, according to Scripture. (see Zech 3:lff)

While Satan is the prosecuting attorney, Michael is the defense attorney (1 Pet 5:8; Jude 9:1; Tim 3:6), because he is the prince who has charge of the people of God (Dan 10:21; 12:1).

As long as there are human sinners to accuse, Satan has a right to be in God's law court.

Vs. 10-12: - These verses let us know why Satan was not "kicked out of court". On earth, prior to the crucifixion, Jesus stood trial for those he represents (namely, his followers including us). He is the Messiah who "gathers into one the scattered children of God" (John 11:52). And so, with Christ's condemnation by the Roman law court (agent of Satan), all people were condemned. Through His death Satan has no more people to accuse because all now are under Christ's authority. So Satan loses his job. (Rom 8:1).

Note: This does not mean that everyone is automatically saved. It means that judgement is now based solely on one's relationship with Christ. So Christ is the Judge, and there is no room for a satanic accuser.

The battle between Michael and Satan is described so briefly in vs. 7-9 because it is the victory and not the gory details of conflict that are important here.