Isaiah 1:27

Zion shall be redeemed with judgment, and her converts with righteousness.

Zion is to be redeemed by judgment, and those who return to her are to be redeemed by righteousness, so that deliverance comes through corrective judgment and right living. The promise belongs to Zion and to her converts together, with redemption reaching both the community and those who come back to it in repentance.

In its setting this redemption follows God turning His hand to purge corruption, thoroughly cleaning out worthless material and removing all impurity. He brings back faithful judges and counselors as at the first, and the result is a city restored and called righteous and faithful, a righteous and loyal community.

It foretells the final deliverance of the saints, for as the plagues on Egypt came just before and during Israel's release from bondage, so the seven last plagues come upon the wicked just before and during the saints' deliverance. For those who handle truth for the world, especially editors and leaders, this requires distinguishing the Lord's work from common affairs. They are to feed the people with real, solid spiritual food that gives strength, rather than acceptable but powerless matter that mixes sacred things with common affairs. They are to give the trumpet a certain sound about Christ's near coming rather than common information, pictures, and sentiments, and to drink deeply from living water through the working of the Holy Spirit.