"Above all, taking the shield of faith." Faith is unbreakable confidence in the personality of God, not in His power. There are some things over which we may lose faith if we have confidence in God's power only. There is so much that looks like the mighty power of God that is not.
We must have confidence in God over and above everything He may do, and stand in confidence that His character is unsullied. Faith stands all tests - "Though He slay me, yet will I trust in Him." When we take the shield of faith, none of these things can get through without breaking the shield. We are protected by the covering shield.
Taken from the book If You Will Ask by Oswald Chambers 1874-1917