Have "your feet shod with the preparation of the gospel of peace" (Eph. 6:15). Elsewhere the Lord has said, "If ye are prepared, ye shall not fear" (D&C 38:30). As we prepare ourselves spiritually, physically, mentally, and emotionally we can better withstand temptations and other things that would lead us away from doing that which is right. When we are prepared we are able to go where and when the Lord will have us go. With what are we prepared? The gospel of peace. It brings peace to our lives and we can use our feet to spread that peace to others as so many LDS missionaries can attest.
"Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked" (Eph. 6:16). In battles, the Roman shield was of key importance. It served to protect most of the body while allowing the legionnaire the attack his enemy. The soldier moved his shield around to ward off blows and even attack the enemy, if necessary. If the armies were farther apart, such as at the beginning of a battle, then small groups of legionaries would often make a testudo, or tortoise, formation in order to protect themselves from arrows. The legionaries in front or on the edges crouched behind their shields, blocking attacks from front. Those behind or in the middle held their shields over their heads and the heads of those in front. This formation was slow but very strong and could withstand serious firepower from the arrows of enemy archers. In general, soldiers could withstand more and stronger attacks as a group than they could individually. Why did Paul say that the shield of faith was most important? Faith in the Lord Jesus Christ is the first principle of the gospel. It is the foundation of the gospel; all other things build upon it. Faith is a shield; it can protect us from onslaughts by the Adversary. It also is stronger when combined with the faith of others - we stand stronger together than we do alone, which is one reason it's important to attend church and be an involved part of a ward.
"Take the helmet of salvation" (Eph. 6:17). Helmets protect the head and brain. Head injuries are usually very serious with the highest rates of fatalities and disability of any injury. The brain controls everything we do. What should we be doing with our brain, how do we protect it? The next verse provides the answer: "Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints" (Eph. 6:18). We should pray always. We should pray not just for ourselves but also for others. Prayer is our method of communication with our Heavenly Father. Through prayer and the spirit and the grace of God we are led to salvation. If we pray for strength and greater faith (which we should) we should always remain humble and ever-reliant on the Lord. As C.S. Lewis once said: "Meanwhile, little people like you and me, if our prayers are sometimes granted, beyond all hope and probability, had better not draw hasty conclusions to our own advantage. If we were stronger, we might be less tenderly treated. If we were braver, we might be sent, with far less help, to defend far more desperate posts in the great battle." (Source). However, as we are faithful, wearing our helmets of salvation, the Lord will be with us just as He was with David facing Goliath or Joshua and his army facing Jericho. When we keep the goals of salvation and exaltation in mind, we do not let anything distract us from doing what is right. With a helmet of salvation we keep our thoughts pure and Christ-centered. Those who are faithful will, in the next life, replace their helmet of salvation with a crown of knowledge (Prov. 14:18), righteousness (D&C 29:13), glory, honor, immortality, and eternal life (D&C 75:5).
Link to the 1st part of this post.