Albert Barnes Commentary Joel 3:20

"But Judah shall abide for ever, and Jerusalem from generation to generation." — Joel 3:20 (ASV)

Judah shall dwell for ever - Not earthly Judah, nor earthly Jerusalem, for these must come to an end, together with the earth itself, whose end the prophets knew well. It is then the one people of God, the true Judah, the people who praise God, the Israel, which is indeed Israel.

Egypt and Edom and all the enemies of God will come to an end; but His people shall never come to an end. The gates of hell shall not prevail against her. The enemy shall not destroy her; time shall not consume her; she shall never decay. The people of God shall abide before Him and through Him here, and shall dwell with Him forever.