The Shield of faith - The scripture says, "Above all, taking the shield of faith." One reason why I believe it says "above all" is because the shield was the most effective of all the armour as it was able to protect the entire body from any blows from a sword or arrows from an archer. This was not a small circular shield but was large and able to cover the entire length of the soldier's body.
We can extract from this and suggest that faith is more important than the other truths identified in the armour - because without it, we can neither access nor apply these truths to our lives.
So let's briefly look at how important faith is...
You cannot receive anything from God without faith - Hebrews 6:12, James 1:6-8
You cannot be justified, made righteous, nor receive salvation without faith - Romans 10:5-17, Galatians 2:16, Galatians 3:1-9
You cannot overcome the trials and tribulations of this world without faith - John 16:33, 1 John 5:4,5
You cannot please God without faith - Hebrews 11:6
Faith is such a big deal that Jesus stated in Luke 18:6-8 that when the Son of man comes, will He really find faith on the Earth? Not, will He find love, will He find soul winners, will He find churches that are filled, etc. But will he find faith!
Out of all the biblical truths - Jesus identifies faith as something that might be lacking when He returns! That's a serious statement.
The bible says in Romans 10:17 that faith comes by hearing and hearing by the word of God; meaning that the word produces faith in our hearts.
So we could say:
You cannot be justified, made righteous, receive salvation, receive anything from God, please God, overcome trials or tribulations - without the Word.
Therefore seeing as faith is so important, and knowing that the word is the only thing that produces faith - it means the word of God (time spent reading the bible, going to church, listening/watching teachings, reading books) should be extremely important to us and made a priority in our lives.