The shield is a broad piece of defensive armour held in hand, generally used in war for the protection of the body. It is a weapon that protects and defends the body. It is a large flat object made of metal or leather that soldiers hold in front of their bodies to protect themselves. It is a device or part of a device that serves as a protective cover or barrier. In short, we can say that the shield protects the soldier from any missile that is thrown at him.
The writer of Hebrews also defines faith in Hebrews 11:1 as the substance of things hoped for, the evidence of things not seen. Do you remember how you felt when you were very young when your birthday approached? You were excited and anxious. You knew you would certainly receive gifts and other special treats. But some things would be a surprise. Birthdays combine assurances and anticipation. Faith is the confidence based on past experiences that God’s new and fresh ideas will surely be ours. Hallelujah!
Apostle Paul uses this imagery of the shield in the hands of the soldier to that of faith. As the shield gives the soldier so much confidence and trust that no weapon will be able to hit him or her, Apostle Paul encourages the Ephesian church to use faith as their shield in their Christian walk. He charges the church in Ephesus to see faith as a shield in their walk with God. Seeing faith as a shield means the believer is completely protected and defended against all the ills of our world if his faith is grounded in the Lord God.
As the main use of the shield is to block any missile that comes at the soldier, the shield is being portrayed here as the only device and weapon that is used to keep away missiles of destruction from our world today. Complete and unshakable faith in Christ Jesus is all that the believer needs to be protected from the threats and the weapons from the camp of the enemy.