What does Isaiah 26:6 mean?
The Lord's people are to put their full trust and hope in Him and Him alone. The "lofty city" (Isaiah 25:2, 12) may seem to be an unstoppable force from an earthly perspective. This city would hint at safety, security, and deliverance from harm. In the end, the Lord will destroy that "lofty" place and the false security it brings. Only the Lord's own city will be secure forever (Isaiah 26:5).Further details are given to that once honored city of the world. Not only will it be cast down, but it will be trampled underfoot by the feet of the "least" important people on earth: those who are poor and in need. Not only will that city of worldliness fail to protect its inhabitants from powerful foreign invaders, but it won't be able to keep out those wandering in looking for food or anything of value.
What is the world city? In Isaiah's time, it may have been a reference to the strength of other nations to protect Israel from powerful enemies. In every era, the world city offers false comfort and security to those who will seek their own good instead of trusting the Lord to provide what they need (1 John 2:15–17).