This is a thought which came up in this morning's Psalms study, which has been a wonderful benefit to me (the class, that is).
"O my Strength, I will watch for You, for You, O God, are my fortress.
My God in His steadfast love will meet me; God will let me look in triumph on my enemies."
This language of God being a "fortress" shows up all over the Psalms. It makes sense, a fortress is a wonderful thing in combat. However, there is one major weakness or liability to the typical fortress. It is stationary. Your castle might be strong, but it isn't mobile.
Yet what do we hear of God, the Fortress? In His steadfast love He will meet me. Our Mighty Fortress isn't just a Fortress, He is a mobile Fortress, not bound and stuck in one place, but ready to be our Fortress wherever we are.
And then of course, there is the wonderful worship image of God in His love coming to meet us and show us mercy - is that not what the Divine Service is? Just a fantastic reminder of how God's care is over and above anything that we on the earth are used to thinking of.