The Whole Armor of God

Why is it important to put on the whole armor of God? We are commanded in several places to put on the whole armor of God, and I believe that the word "whole" was chosen deliberately. It doesn't make a lot of sense to march into battle only partially armored. In a fight to the death both sides are going to look for any advantage they can find, so if your arms or your back or your head isn't protected, that's where the enemy is going to strike, rather than trying to hack through the armor you do have. It makes sense to focus on the parts of the gospel that naturally come easy to us, to obey the commandments that make sense to us, to love the neighbors we like. We can sit there and improve our helmet of salvation until it looks like something Iron Man would wear, but if we've neglected entirely the breastplate of righteousness, then that iron man helmet isn't going to do us much good when the enemy stabs us in the heart. It is better to have on the whole armor of God, even if certain pieces are less impressive than others, than to have focused all our efforts into making our shield of faith reinforced with diamonds but not having anything to protect our legs. It is hard to acknowledge our weaknesses, but if we come to the Lord with humility and faith and hope, He can make weak things strong unto us and He will lovingly show us which pieces of His armor we have been neglecting.