12:1 A great and wondrous sign [portent pointing to something beyond itself] appeared in heaven: [first sign a spiritual representation of Jesus’ birth] a woman [perhaps represents Israel through whom the Messiah came into the world] clothed with [note emblems of light] the sun, with the moon under her feet and a crown of twelve stars [relates woman to twelve tribes of Israel] on her head.
Note: Satan is not omniscient, omnipresent, or omnipotent as God is; but he is extremely crafty and powerful.
12:2 She was pregnant and cried out in pain as she was about to give birth [Israel pictured as a woman in labor (cf. Mic. 4:10; 5:2-3)].
12:3 Then [second sign describes Satan in symbolic terms] another sign appeared in heaven: an enormous red [signifies blood shed by murderous/destructive work of Satan] dragon [common figure to portray evil in apocalyptic literature; Satan; all forces of evil represented in this dragon] with seven heads [indicates great wisdom] and ten [number of human completion] horns [symbol of power or perhaps complete human power; in case of Satan, great destructive power] and seven crowns [symbol of authority over kingdom of darkness and evil] on his heads.
12:4 His tail swept a third of the stars [some believe a reference to Satan taking one third of angels with him when he fell from heaven; cf. Isa. 14:12-15] out of the sky and flung them to the earth. The dragon [cf. (KJV) Ezek. 29:3 re: Pharaoh as dragon and Jer. 51:34 re: Nebuchadnezzar as dragon who gulped Jerusalem / both enemies of Israel] stood in front of the woman who was about to give birth, so that he might devour [refers to Satan’s primary interest / attempt to kill Jesus from the moment of His birth and to frustrate God’s redemptive work; see Matt. 2:16-17 re: Herod’s attempt to kill Jesus] her child the moment it was born.
12:5 [completion of first vision] She gave birth to a son [incarnation; cf. Jn. 1:14], a male child [symbolizes Jesus (as per all millennial views)], who will rule all the nations with an iron scepter [see Rev. 2:27 and 19:15; cf. Ps. 2:9]. And her child was [fill in story of Jesus from Gospels from birth to ascension] snatched up to God and to His throne [evil defeated; allusion to God’s victory over Satan by resurrection and ascension of Christ].
12:6 The woman fled into the desert to a place prepared for her by God, where she might have taken care of for 1,260 days.
Note: Verses 7-12 explain Satan’s hostility.
12:7 And there was war in heaven [some believe took place prior to creation (Isa. 14:12); some believe occurred after ascension of Christ; others see as reference to some future event]. Michael [Israel’s guardian as per Dan. 10:13,21; 12:1; archangel or chief angel according to Jude 9] and his angels fought against the dragon [Satan], and the dragon and his angels [cf. 12:4] fought back.
12:8 But he [Satan] was not strong enough, and they lost their place in heaven [indicates complete defeat; Satan’s defeat in heaven assures church’s victory on earth].
12:9 The great dragon was hurled down – that ancient serpent called the devil [means accuser or slanderer], or Satan [means adversary or opponent], who leads the whole world astray [part of Satan’s agenda]. He was hurled [cast out of heaven; banished from God’s presence] to the earth [cf. 1 Jn. 5:19], and his angels with him.
12:10 Then I heard a loud voice in heaven say [proclamation of praise]: “Now have come the salvation and the power and the kingdom of our God, and the authority of His Christ. For the accuser [implies continual action] of our brothers, who accuses them before our God day and night [continuously], has been hurled down.
12:11 They overcame him [Satan]  by the blood of the Lamb [sacrificial/redemptive death of Christ on the cross; guarantee of our acceptance with God] and  by the word of their testimony [personal affirmation that we have been redeemed by the blood of the Lamb; perhaps affirmation that “Jesus is Lord” as opposed to “Caesar is Lord”];  they did not love their lives so much as to shrink from death [in the face of persecution].
12:12 Therefore rejoice [Satan’s expulsion brought joy in heaven], you heavens and you who dwell in them! But woe to the earth and the sea, because the devil has gone down to you! He is filled with fury [turbulent anger, particularly against believers], because he knows that his time is short.”
12:13 When the dragon saw that he had been hurled to the earth, he pursued the woman who had given birth to the male child.
12:14 The woman was given the two wings of a great eagle, so that she might fly to the place prepared for her in the desert, where she would be taken care of for a time, times and half a time, out of the serpent’s reach.
12:15 Then from his mouth the serpent spewed water like a river, to overtake the woman and sweep her away with the torrent.
12:16 But the earth helped the woman by opening its mouth and swallowing the river that the dragon had spewed out of his mouth.
12:17 Then the dragon was enraged at the woman [Satan failed to prevent mission of the woman’s child] and went off to make war [methods related in following chapters] against [cf. 1 Pet. 5:8; Eph. 6:10-20] the rest of her offspring [believers; the church] – [What kind of believers experience Satan’s fury most? …] those [refers to believers] who obey God’s commandments and hold to the testimony of Jesus.