The size of our shield increases in proportion to our faith. Paul said that “over” all, take up the shield of faith. Another way of looking at “over all” is to say covering all. This much like the very large Roman shields of that day–a huge taller than our body shield.
That the size of our covering or shield was in proportion to our faith is also what Jesus spoke of when He said if we had the faith of a mustard seed, then… So if we had the faith, we would be able to receive the full scale of His Shielding. Now of course, God shields us even when we are not even aware of it; however, Paul is talking about “taking up” this shield. So that this is shield we actually activate by faith.
Do we have the level of faith to take up the full grand scale of the shielding made available to us? This is what Paul is mustering us up to do–increase our faith until a huge portion of Christ is actually made manifest as our shield…His Shield is as big as we are able to allow it to be. If it were allowed in by faith, the shield itself could push a mountain aside, or raise a dead man, or…David said that God WAS His shield, His buckler, His Strength. To the degree that God is allowed to be by faith, we will be be shielded.