10 Finally, be strong in the Lord and in the strength of his might. 11 Put on the whole armour of God, that you may be able to stand against the schemes of the devil.12 For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. 13 Therefore take up the whole armour 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."
Ephesians 6:10-18
There are two preliminary considerations that we must look at before going any further. This is not the first time in the epistle that Paul refers to the evil one, for in 2:2 he has spoken of 'the prince of the power of the air'. There, however, he has mentioned him almost in passing, as one element among others describing the plight of man in his sin. But here, in 6:10ff, Paul brings him right out into the open, and reminds us that Christians, who are called 'saints' in the opening verses of the epistle, are also called to be 'soldiers', and that they are beset by the host of evil under their dreadful king, and that it will be all they can do to hold their ground, in unshaken fidelity to their divine Commander, as Handley Moule puts it in his commentary. Paul then is reminding the Ephesians that the life of fullness which he has been expounding is all the while to be lived on hostile ground, and in face of organised assaults made by unseen personal adversaries. As Moule puts it, this is 'an urgent reminder of the infinitely serious conditions under which the bright secrets of grace are to be lived out. The Christian is not only a servant but also a soldier; he belongs not only to a home ("an habitation of God through the Spirit") but also to a citadel. And to recollect the formidable surroundings is of course vitally necessary if the life lived amidst them is not to be swept away in ruin. That is the first preliminary consideration; and the second is this: Paul leaves this issue of the dark powers to the end of the epistle, and it seems to us that this is the proper place for it, for the whole subject of the dark powers must not be allowed to become a preoccupation and obsession, assuming a wholly disproportionate place in our thinking that obscures the infinitely greater reality that Jesus Christ has conquered Satan. This is the greatest and most important witness the New Testament bears concerning the dark powers, and this is the true perspective that we are given here by Paul.'