Shield of Faith

Paul writes to the Ephesians to put before them the shield of faith. The shield went before the body and even the sword to protect the soldier from the first attacks. The shield itself could also be used as a offensive piece of armor by forming a barricade with a multitude of shields.
Likewise, the shield of faith should go before us as we encounter spiritual warfare. Hebrews 11:1 says

Faith is confidence in what we hope for and assurance about what we do not see

Our faith should be what we build up and strengthen so that no one may destroy what we believe. Though we cannot see Jesus or the Holy Spirit, we still believe because of our hope and faith that Jesus came and died for the sin of man in the past present and future. As Christians we should have confidence in that fact and assurance in the quiet words spoken but not seen given by the Spirit.
The reason the shield was listed before the sword of the spirit (which will be expounded upon in a few weeks), is because before you may go out and use the Holy Spirit you must have a strong foundation of faith behind you. We gain faith by learning more about the character of God through The Word and through resting in His presence. If we try to pour into others and use the sword of the spirit without a strong faith we very well may end up speaking a false gospel, or we will be empty with no real truth to share with those around us.
An example in the Old Testament is in Daniel 3 is Shadrach, Meshach and Abed-Nego in the fiery furnace. These men are the only three listed in the Bible who, in faith, refused to bow to the idol that King Nebuchadnezzar demanded they worship. They were then thrown into a furnace but God did not allow them to be swallowed by the flames and they lived! This is an excellent testament to the faith that we are called to have as children of God. These men had faith in what they could not see, and through that we saw the power of God. Romans 8:24-25 says that,

“For we were saved in this hope, but hope that is seen is not hope; for why does one still hope for what he sees? But if we hope for what we do not see, we eagerly wait for it with perseverance”

The men were not hoping for what they already have, but for what God has promised to those that love Him. He has promised to be consistent and ever-present in our lives regardless of what we do or how many times we mess up.

Daniel 3:17-18
“If that is the case, our God whom we serve is able to deliver us from the burning fiery furnace, and He will deliver us from your hand, O king. But if not, let it be known to you, O king, that we do not serve your gods, nor will we worship the gold image which you have set up.”

This passage from the Old Testament reminds us that our lives should be marked by day in day out obedience to the word of God that comes from faith. We should expect the ordinary while praying for the extraordinary to take place, like Daniel after being rescued from a BURNING furnace!
The shield of faith is what defines our character as believers. We must use our foundation in the Word to protect ourselves before we can go out in obedience and use the sword of the spirit to spread His Word.