John Gill Bible Commentary

They saw it,.... Either the city or the power of God, as Aben Ezra; or, as Jarchi, God himself going forth to fight against the nations. This refers to the power Christ will take to himself, and show forth, by reigning in his church, and protecting it, which will not only be visible to the saints, but to the nations of the world; and to the brightness of Christ's coming in his spiritual reign, with the lustre of which antichrist will be destroyed, Rev 11:17; and to the glorious state of the church, signified by the rising of the witnesses, and their standing on their feet, and ascending to heaven, which will be seen by their enemies, Rev 11:11; and to the destruction of Rome, the smoke of whose burning, the kings of the earth, that have committed fornication with her, will see and lament, Rev 18:8; and so their marvelled: at the glory of the church, the security of it, the power of Christ in it and over it, and at the destruction of mystical Babylon; see Isa 52:14; they were troubled: as Herod and all Jerusalem were, upon hearing of the birth of Christ, Mat 2:3; so these kings will be, upon seeing the coming and power of Christ in the latter day, the invincibleness of his church, and their own immediate and utter ruin: this will be the time or the howling of the shepherds, both civil and ecclesiastical, when all hands will be faint, and every man's heart will melt, Zac 11:2; and hasted away: fled for fear of the great King at the head of his armies, in the defence of his church and people: and as the kings of the earth also at the destruction of Rome will flee and stand afar off, for fear of her torment, Rev 18:10.