Ephesians 6:13–18 (ESV)
13 Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. 14 Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, 15 and, as shoes for your feet, having put on the readiness given by the gospel of peace. 16 In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; 17 and take the helmet of salvation, and the sword of the Spirit, which is the word of God, 18 praying at all times in the Spirit, with all prayer and supplication. To that end, keep alert with all perseverance, making supplication for all the saints
 
We are examining each individual piece of armor, so that we can fight the battles that lie ahead and win.
 
The first four are defensive weapons, which have to do with living a life of truthfulness, righteousness, peace and faith. Then, we looked at two of the three offensive weapons: the helmet of salvation and the sword of the Spirit.
 
As verse 17 rightly explains, the sword represents the Word of God. Yesterday, we took time to see how Jesus used this weapon against the devil when temped in the wilderness.
 
We are now ready to examine the final weapon of war. Even though Paul does not use a piece of the soldiers’ attire, it is plain that prayer is probably the most significant part of winning the battle. In fact, notice how costly he ties prayer to the Word of God.
 
verse 17 “and take…the sword of the Spirit, which is the word of God, 18 praying at all times in the Spirit, with all prayer and supplication.”
 
While prayer is not mentioned as a part of the armor, we might look at its importance as the atmosphere in which the soldier must live and breathe. It is the spirit in which he must don the armor and face the enemy. Prayer should be continual, not sporadic; a habit, not an isolated act.
 
Notice that the soldier should use all kinds of prayer: public and private; deliberate and spontaneous; supplication and intercession; confession and humiliation; praise and thanksgiving.
And prayer should be in the Spirit, that is, inspired and led by Him.
 
These are not to be prayers recited merely by rote (without giving thought to their meaning)—of what value are they in combat against the hosts of hell?
 
“There must be vigilance in prayer: watchful to this end. We must watch against drowsiness, mind-wandering, and preoccupation with other things. Prayer requires spiritual keenness, alertness, and concentration. And there must be perseverance in prayer. We must keep on asking, seeking, knocking (Luke 11:9). Supplication should be made for all the saints. They are engaged in the conflict too, and need to be supported in prayer by their fellow soldiers.” (William MacDonald, Believer’s Bible Commentary: Old and New Testaments)
 
Was Paul preaching without practicing what he taught? Well, look how he began his letter to the Ephesians.
 
Ephesians 1:16–23 (ESV)
16 I do not cease to give thanks for you, remembering you in my prayers, 17 that the God of our Lord Jesus Christ, the Father of glory, may give you the Spirit of wisdom and of revelation in the knowledge of him, 18 having the eyes of your hearts enlightened, that you may know what is the hope to which he has called you, what are the riches of his glorious inheritance in the saints, 19 and what is the immeasurable greatness of his power toward us who believe, according to the working of his great might 20 that he worked in Christ when he raised him from the dead and seated him at his right hand in the heavenly places, 21 far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in the one to come. 22 And he put all things under his feet and gave him as head over all things to the church, 23 which is his body, the fullness of him who fills all in all.
 
What a prayer! What a prayer warrior! Paul clearly understood that the battle is won, not by the armor alone, but by the prayerful life of the one who wears the armor.