Put on the whole armor. God has furnished us with various defensive weapons, provided we do not indolently refuse what is offered. But we are almost all chargeable with carelessness and hesitation in using the offered grace; just as if a soldier, about to meet the enemy, should take his helmet, and neglect his shield. To correct this security, or, we should rather say, this indolence, Paul borrows a comparison from the military art, and bids us put on the whole armor of God. We ought to be prepared on all sides, so as to want nothing. The Lord offers to us arms for repelling every kind of attack. It remains for us to apply them to use, and not leave them hanging on the wall. To quicken our vigilance, he reminds us that we must not only engage in open warfare, but that we have a crafty and insidious foe to encounter, who frequently lies in ambush; for such is the import of the apostle's phrase, THE WILES [1] (tas methodeias) of the devil

Footnotes

1 - "Plutarch tells us, (Symp. l. 2., page 638,) that wrestling was the most artful and subtle of all the ancient games, and that the name of it (pale) was derived from a word, which signifies to throw a man down by deceit and craft. And it is certain that persons who understand this exercise have many fetches, and turns, and changes of posture, which they make use of to supplant and trip up their adversaries. And it is with great justice, that a state of persecution is compared with it; since many are the arts, arising from the terrors of worldly evil on the one hand, and the natural love which men have to life, liberty, plenty, and the pleasures of life, on the other, that the devil makes use of to circumvent and foil them." -- Chandler.

Put on the whole armor of God - The whole description here is derived from the weapons of an ancient soldier. The various parts of those weapons - constituting the "whole panoply" - are specified in Ephesians 6:14-17. The word rendered "whole armor" πανοπλίαν panoplian, "panoply"), means "complete armor," offensive and defensive; see Luke 11:22; Romans 13:12 note; 2-Corinthians 6:7 note. "The armor of God" is not that which God wears, but that which he has provided for the Christian soldier. The meaning here is:
(1) that we are not to provide in our warfare such weapons as people employ in their contests, but such as God provides; that we are to renounce the weapons which are carnal, and put on such as God has directed for the achievement of the victory.
(2) we are to put on the "whole armor." We are not to go armed partly with what God has appointed, and partly with such weapons as people use; nor are we to put on "a part" of the armor only, but the "whole" of it. A man needs "all" that armor if he is about to fight the battles of the Lord; and if he lacks "one" of the weapons which God has appointed, defeat may be the consequence.
That ye may be able to stand - The foes are so numerous and mighty, that unless clothed with the divine armor, victory will be impossible.
Against the wiles of the devil - The word rendered "wiles" (μεθοδεία methodeia), means properly that which is traced out with "method;" that which is "methodized;" and then that which is well laid - art, skill, cunning. It occurs in the New Testament only in Ephesians 4:14, and in this place. It is appropriately rendered here as "wiles," meaning cunning devices, arts, attempts to delude and destroy us. The wiles "of the devil" are the various arts and stratagems which he employs to drag souls down to perdition. We can more easily encounter open force than we can cunning; and we need the weapons of Christian armor to meet the attempts to draw us into a snare, as much as to meet open force. The idea here is, that Satan does not carry on an open warfare. He does not meet the Christian soldier face to face. He advances covertly; makes his approaches in darkness; employs cunning rather than power, and seeks rather to delude and betray than to vanquish by mere force. Hence, the necessity of being constantly armed to meet him whenever the attack is made. A man who has to contend with a visible enemy, may feel safe if he only prepares to meet him in the open field. But far different is the case if the enemy is invisible; if he steals upon us slyly and stealthily; if he practices war only by ambushes and by surprises. Such is the foe that we have to contend with - and almost all the Christian struggle is a warfare against stratagems and wiles. Satan does not openly appear. He approaches us not in repulsive forms, but comes to recommend some plausible doctrine, to lay before us some temptation that shall not immediately repel us. He presents the world in an alluring aspect; invites us to pleasures that seem to be harmless, and leads us in indulgence until we have gone so far that we cannot retreat.

Put on the whole armor of God - Ενδυσασθε την πανοπλιαν του Θεου. The apostle considers every Christian as having a warfare to maintain against numerous, powerful, and subtle foes; and that therefore they would need much strength, much courage, complete armor, and skill to use it. The panoply which is mentioned here refers to the armor of the heavy troops among the Greeks; those who were to sustain the rudest attacks, who were to sap the foundations of walls, storm cities, etc. Their ordinary armor was the shield, the helmet, the sword, and the greaves or brazen boots. To all these the apostle refers below. See on Ephesians 6:13 (note).
The wiles of the devil - Τας μεθοδειας του διαβολου· The methods of the devil; the different means, plans, schemes, and machinations which he uses to deceive, entrap, enslave, and ruin the souls of men. A man's method of sinning is Satan's method of ruining his soul. See on Ephesians 4:14 (note).

Put on the whole armour of God,.... Not that which God himself is sometimes clothed with, and uses against his enemies; but what he has provided for his people, and furnishes them with; the particulars of which are after mentioned: and it is called "the armour of God", because it is prepared by him for his people, and is bestowed on them by him; and because it is in its own nature divine and spiritual, and not carnal; and because it is provided for fighting the Lord's battles, and is used in them; and because the efficacy of it is from him, and the execution it does is owing to him: and it is whole, complete, and perfect; and all of it is useful, and no part to be neglected, but all to be taken and "put on"; which is not to make and provide this armour, but to take it, as in Ephesians 6:13; as being ready made and provided, and to expect and prepare for battle, and make use of it; and this supposes saints to be in a warfare state, and that they are in the character of soldiers, and have enemies to fight with, and therefore should be accoutred with proper and suitable armour, to meet them:
that ye may be able to stand against the wiles of the devil; who is the grand enemy of Christ and his people, and a very powerful and cunning one he is; so that the whole armour of God should be put on, which is proof against all his might and craft, in order to stand against him, oppose him, and fight, and get the victory over him, which in the issue is always obtained by believers; for they not only stand their ground in the strength of Christ, and by the use of their armour confound his schemes, and baffle all his arts and stratagems, but are more than conquerors through him that has loved them.

the whole armour--the armor of light (Romans 13:12); on the right hand and left (2-Corinthians 6:7). The panoply offensive and defensive. An image readily suggested by the Roman armory, Paul being now in Rome. Repeated emphatically, Ephesians 6:13. In Romans 13:14 it is, "Put ye on the Lord Jesus Christ"; in putting on Him, and the new man in Him, we put on "the whole armor of God." No opening at the head, the feet, the heart, the belly, the eye, the ear, or the tongue, is to be given to Satan. Believers have once for all overcome him; but on the ground of this fundamental victory gained over him, they are ever again to fight against and overcome him, even as they who once die with Christ have continually to mortify their members upon earth (Romans 6:2-14; Colossians 3:3, Colossians 3:5).
of God--furnished by God; not our own, else it would not stand (Psalm 35:1-3). Spiritual, therefore, and mighty through God, not carnal (2-Corinthians 10:4).
wiles--literally, "schemes sought out" for deceiving (compare 2-Corinthians 11:14).
the devil--the ruling chief of the foes (Ephesians 6:12) organized into a kingdom of darkness (Matthew 12:26), opposed to the kingdom of light.

Put on the whole armor of God. The ancient soldier was not equipped for war until he had put on his armor. Paul was at that time a prisoner, probably living near the prÃ&brvbr;torian camp in Rome, as he was by the Roman customs under the charge of the prÃ&brvbr;torian prefect. It is possible that the figure was suggested by the sights he so often witnessed.
Against the wiles of the devil. The great enemy. The armor was designed not only to protect, but there were weapons also with which to assail him.
For we wrestle. Fights then were a hand to hand grapple.
Not against flesh and blood. While flesh and blood may seem to assail us, the real enemies are evil spiritual powers.
Principalities and powers. These terms designate different rank of evil spirits. These were fallen angels. In Ephesians 1:21, the same terms are applied to the different ranks of holy angels.
Against the rulers of the darkness of this world. Satan is described as the ruler of this world (John 12:31; John 14:30; John 16:11) and the god of this world (2-Corinthians 4:4). He uses for his dominion not only evil spirits, but wicked men, and his sway is darkness rather than light.
Spiritual wickedness. See the Revision. It is likely that the meaning is the same as in Ephesians 2:2. The high places, the air, is a dwelling-place and medium of these evil influences.
Wherefore, take unto you. Seeing you have such enemies, arm! Put on the whole armor of God.
In the evil day. The day of peril and assault.
To stand. To stand the assault, and to stand victorious, when it is beaten back.

Put on the whole armour of God - The Greek word means a complete suit of armour. Believers are said to put on the girdle, breastplate, shoes; to take the shield of faith, and sword of the Spirit. The whole armour - As if the armour would scarce do, it must be the whole armour. This is repeated, Ephesians 6:13, because of the strength and subtilty of our adversaries, and because of an "evil day" of sore trial being at hand.