A warning 26:20-21

The prophet now addressed his people rather than God.

26:20 Before the restoration of Israel, however, God's people would experience hard times (in the Tribulation, cf. Rev. 12). Before God opened the gates of the new city to the redeemed (v. 2), they would need to shut their doors against their foes (cf. Gen. 7:1, 16; Exod. 12:22-23). Shutting the doors suggests both safety from danger and separation from others, in this case pagans.

26:21 Yahweh would come out of His heavenly place of quiet to punish earth-dwellers for their secret sins in the Tribulation. The earth itself, the forces of nature, would assist the Lord, metaphorically, by exposing sins that lay hidden (cf. v. 12).