Revelation 12:10

And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.

Now. Now that Satan is cast out of heaven. Primarily at Jesus' resurrection and ascension: Jesus' rise is Satan's fall. Matthew 28:18, "All power [ exousia (G1849), 'authority,' as here] is given unto me in heaven and in earth:" connected with Revelation 12:5, "her child was caught up unto God and to His throne." In the ulterior sense, just before Christ's coming, when Israel shall be restored as mother-church of Christendom, Satan, who resisted her restoration on the ground of her unworthiness, is cast out by Michael, (note, Revelation 12:7). This is preliminary to the glorious event similarly expressed (Revelation 11:15), "The kingdom of this world is become (the very word here [ egeneto (G1096)], 'is come') our Lord's and His Christ's:" Israel resuming her place.

Salvation ... - `the salvation (namely, fully, finally, Hebrews 9:28: cf. Luke 3:6; hence, not until now do the blessed raise the fullest hallelujah for salvation to the Lamb, Revelation 7:10; Revelation 19:1), the power [ dunamis (G1411)], and the authority [ exousia (G1849): legitimate] of His Christ.

Accused them before our God day and night - hence, the need that the oppressed Church, God's own elect (the widow, Luke 18:1, continually coming, so as even to weary the unjust judge), should cry day and night unto Him.