Just as these shields were more effective when the soldiers marched together, our spiritual shields are more effective when we march with fellow believers – holding each other accountable, encouraging one another, and watching each other’s backs. The dark forces of the earth will throw darts of temptation in a constant barrage, hoping that one will find a break in the shields to start a destructive fire in our lives.
Roman helmets would be either like the molded plumed helmets you see in movies or leather with metal attached. It protected the soldier from attack by a broad sword swinging down from above. As the forces of Satan try to smash us with doubt and depression, the helmet of salvation is our protection. We know that no matter what happens to us on earth, our hope is in heaven. We know that a place is prepared for us there. Our treasure and reward are not of this earth. We fervently believe that one day evil will be destroyed and good will triumph. Our salvation is secure.
The sword carried by Roman soldiers for hand to hand combat would be sheathed in the belt that held together their tunic. The sword of the Spirit is the word of God, and it is carried in the belt of truth. Swords are both offensive and defensive; they can strike a blow as well as parry. We must be knowledgeable about all of Scripture in order to use the weapon effectively. When Satan tempted Jesus in the wilderness, Jesus immediately quoted verses from Deuteronomy that contradicted the tempter’s twisted theology. He didn’t have to pull up the ancient scroll app on his Smartphone and search for “temping the Lord your God.” Word here is rhema which means a specific utterance. You have to know the scripture that applies to the specific battle you are in. You can’t just go around quoting John 3:16 all the time and expect to battle effectively.
I don't know if we even understand the fullness of what it means to have the sword of the Spirit. I'm quite confident we don't. This incredible, matchless, incomparable book is the final weapon, the final element of armor given to the believer in the battle against Satan. And the sad fact is that so many Christians do not really know how to use it. We fall victim to Satan because of ineptness with the sword. Do you realize what kind of a book this is? Do you really realize what you have in your hand as you glance at its words and its pages? Let me just tell you. Let me tell you what the Bible claims for itself… This book can bring you to salvation and bring you to perfection. There is nothing other than that that is needful. So the Bible is infallible in total, inerrant in part, complete, authoritative and sufficient… effective and divine… What a person does with a Bible reveals his relationship to God. You can’t just pick your Bible up and flail it in the air. It’s not some great broad sword. It has to be used with precision - John MacArthur