I've heard many theories about why there is no mention of armor for our backs and each of them made sense to me. I suppose there could be more than one reason for it. Allow me to add my opinion to the mix. I believe that the reason no mention is made for there being armor for our backs is that we are the armor for each other's backs. I believe that as Christians, you have my back and I have yours! At least, that's how it should be. I believe that the reason the devil sneaks up and overtakes our brothers and sister so often is because we are not covering each other's backs as we ought! One of the last verses in Ephesians says that we should be watching thereunto with all perseverance and supplication for all saints.
When we pray, we should always make mention of our brothers and sisters all around the world. Some of them are literally dying for the sake of Christ! The Bible says all perseverance and all saints! Whatever blessings we ask from God for ourselves, we should ask for our brothers and sisters also. I'm expecting you to cover my back and you can count on me to cover yours!