This verse looks to the day when the Lord will slay Leviathan (an ancient symbol of chaos and evil), thus securing a decisive victory over His foes.
The Restoration to Come in the Day of the Lord
What will characterize God’s people after His judgment?
Isaiah 27 looks to the day when God’s favor will return to His people. God’s favor will not return however, until after His judgment has been executed.
Isaiah 5:1-7 contains the parable of the worthless vineyard (Israel) and the decision of the owner of the vineyard to abandon it (refer to pages 6-7 of these notes). Isaiah 27 contains the account of a vineyard (Israel as per 27:6) that is pleasant, productive, and worth protecting. This was a wonderful message of hope for Isaiah’s listeners.
But such hope would not be realized automatically. God would punish His people, though not as severely as their enemies (27:7-8), to the end that they would abandon their worship of false gods (27:9). Failure to correct their course would result in a grim instead of a glorious future (27:10-11). In that day, God will sound the trumpet to summon the exiles home to Jerusalem to worship Him (27:12-13).