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.
14 Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness,
15 and having shod your feet with the preparation of the gospel of peace;
16 above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one.
17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God;
Paul was in prison when he wrote this letter to the Ephesians. He was guarded by Roman soldiers all the time. It’s entirely possible that there was a fully-equipped soldier in the room with him as he was writing this.
therefore (v.13) = on this account — because our fight is with Satan
take up (v.13) = take up in order to use, take up and put on — the tense indicates a command to be obeyed at once, like an order in the military — to be done immediately and once for all
This is something very different from the garments in which we stand before God through grace. Every one of us who have put our trust in the Lord Jesus Christ has been made the righteousness of God in Him, the best robe is His. We stand before God in Christ, but we do not put this on ourselves. God has clothed us. But when it comes to the panoply for conflict, we need to put on each separate piece of armor in order to withstand in the evil day. — Ironside, page 316.
withstand (v.13) = stand against, resist oppose
evil (v.13) = evil in active opposition to the good
done (v.13) = perform, accomplish, achieve
girded your waist (v.14) — His belt was no mere adornment of the soldier, but an essential part of his equipment. Passing round the loins and by the end of the breastplate (in later times supporting the sword), it was of especial use in keeping other parts in place, and in securing the proper soldierly attitude and freedom of movement. — Wuest, page 143.
truth (v.14) = openness, sincerity, truthfulness, reality — without deceit or attempt to disguise
righteousness (v.14) — not the justifying righteousness of salvation but that of sanctification — moral rectitude
He saw that there was no man, and wondered that there was no intercessor; therefore His own arm brought salvation for Him; and His own righteousness, it sustained Him. For He put on righteousness as a breastplate, and a helmet of salvation on His head; He put on the garments of vengeance for clothing, and was clad with zeal as a cloak (Isaiah 59:16-17).
Isaiah speaks here of the Messiah, our blessed Lord. He put on righteousness as a breastplate. That is something different from what was always His in eternity. He came into this world as a Man, and, as a man, was obedient in all things to the will of God. He put on righteousness as a breastplate, and now you and I are called to imitate Him by putting on the breastplate of righteousness. — Ironside, pages 321-322
feet (v.15) — The Roman soldier word sandals which were bound by thongs over the instep and around the ankle, and the soles were thickly studded with nails. This would give him a firm footing in case of attack. The word “preparation” is hetoimazo, which was used in classical Greek in the sense of establishment or firm foundation. Thus, the Christian soldier should see to it that his feet are equipped with the sandals which will give him a firm footing, namely, the good news that speaks peace to a sinful heart, for the Lord Jesus made peace by the blood of His Cross, making a way for a holy God to reunite Himself with a believing sinner who in Adam had been separated from Him, and His life. The Greek word “peace” is eirene, and means “that which has been bound together.” The preparedness, the mental alacrity with which we are inspired by the gospel with its message of peace with God, is to be to us the protection and equipment which the sandals that cover the feet are to the soldier. With this we shall be helped to face the foe with courage and with promptitude. — Wuest, page 144