We have a strong city; God makes salvation its walls and ramparts.

What an incredible picture this is – a strong city, impenetrable, able to withstand not only the battles outside the walls, but also any within the walls.  Salvation is the wall that surrounds the city, and makes it impossible for the enemy to enter.  It is also salvation that fortifies the city within its own walls.  We are secure in Christ.  Our own individual cities are protected and sustained by the walls of salvation.  The owner of our city is Christ; the mayor is the Holy Spirit.  God is our governor.  These truths make vs. 3 come alive.  vs. 3 You will keep in perfect peace him whose mind is steadfast because he trusts in you.