The following is an excerpt from The MacArthur New Testament Commentary on Ephesians 6.

And take the helmet of salvation, (6:17a)

The fifth piece of God’s armor is represented by the Roman soldier’s helmet, without which he would never enter battle. Some of the helmets were made of thick leather covered with metal plates, and others were of heavy molded or beaten metal. They usually had cheek pieces to protect the face.

The purpose of the helmet, of course, was to protect the head from injury, particularly from the dangerous broadsword commonly used in the warfare of that day. That was not the much smaller sword mentioned later in this verse, but was a large two–handed, double–edged sword (rhomphaia, see Rev. 1:16; 2:12; 6:8) that measured three to four feet in length. It was often carried by cavalrymen, who would swing at the heads of enemy soldiers to split their skulls or decapitate them.

The fact that the helmet is related to salvation indicates that Satan’s blows are directed at the believer’s security and assurance in Christ. The two dangerous edges of Satan’s spiritual broadsword are discouragement and doubt. To discourage us he points to our failures, our sins, our unresolved problems, our poor health, or to whatever else seems negative in our lives in order to make us lose confidence in the love and care of our heavenly Father.

Since Paul is addressing believers, putting on the helmet of salvation cannot refer to receiving Christ as Savior. The only ones who can take up any piece of God’s armor, and the only ones who are involved in this supernatural struggle against Satan and his demon forces, are those who are already saved.

Trusting in Jesus Christ, immediately saves from the penalty of sin. For believers, this first aspect of salvation, which is justification, is past. It was accomplished the moment we trusted in Christ, and that particular act of faith need never be repeated, because we are secure in our Father’s hands—from whom, as we have just seen, we can never be snatched (John 10:28–29). We are forever saved from condemnation (Rom. 8:1).

The second aspect of salvation, which is sanctification, involves our life on earth, during which time we experience a measure of freedom from the dominating power of sin. Being now under God’s grace, sin no longer has mastery or dominion over us; we are no longer sin’s slave but God’s (Rom. 6:14, 18–22). Paul shows these first two aspects of salvation side by side in the previous chapter of Romans: “For if while we were enemies, we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life” (5:10). Christ’s death saved us once and for all from sin’s penalty, and His life within us now is saving us day to day from sin’s power and mastery.

The third aspect of salvation is future, the aspect of glorification, when we shall one day be saved altogether and forever from sin’s presence. Looking forward to that glorious time, John says, “Beloved, now we are children of God, and it has not appeared as yet what we shall be. We know that, when He appears, we shall be like Him, because we shall see Him just as He is” (1 John 3:2). To be like God is to be without sin. We rejoice that this aspect of our salvation “is nearer than when we believed” (Rom. 13:11).

It is this final aspect of salvation that is the real strength of the believer’s helmet. If we lose hope in the future promise of salvation, there can be no security in the present. This, no doubt, is why Paul calls this same piece of armor “the helmet” which is “the hope of salvation” (1 Thess. 5:8). “Having the first fruits of the Spirit,” Paul explains in Romans, “even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body. For in hope we have been saved” (8:23–24). The helmet of salvation is that great hope of final salvation that gives us confidence and assurance that our present struggle with Satan will not last forever and we will be victorious in the end. We know the battle is only for this life, and even a long earthly life is no more than a split second compared to eternity with our Lord in heaven. We are not in a race we can lose. We have no purgatory to face, no uncertain hope that our own continued efforts or those of our loved ones and friends will perhaps some day finally make us acceptable to God. We know that whom God “predestined, these He also called; and whom He called, these He also justified; and whom He justified, these He also glorified” (Rom. 8:30). There is not the loss of a single soul from predestination to justification to sanctification to glorification. That is God’s unbroken and unbreakable chain of salvation (cf. John 6:39–40; 10:27–30).

We have a certain hope, “a living hope,” as Peter calls it. “Blessed be the God and Father of our Lord Jesus Christ,” he exults in his first epistle, “who according to His great mercy has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, to obtain an inheritance which is imperishable and undefiled and will not fade away, reserved in heaven for you, who are protected by the power of God through faith for a salvation ready to be revealed in the last time” (1 Pet. 1:3–5). When the helmet of that hope is in place, we can “greatly rejoice, even though now for a little while, if necessary, [we] have been distressed by various trials, that the proof of [our] faith, being more precious than gold which is perishable, even though tested by fire, may be found to result in praise and glory and honor at the revelation of Jesus Christ; and though [we] have not seen Him, [we] love Him, and though [we] do not see Him now, but believe in Him, [we] greatly rejoice with joy inexpressible and full of glory, obtaining as the outcome of [our] faith the salvation of [our] souls” (vv. 6–9). That is the salvation which is our helmet. Our helmet is the certain prospect of heaven, our ultimate salvation, which “we have as an anchor of the soul” (Heb. 6:19).

Often when a runner is on the home stretch of a race he suddenly “hits the wall,” as the expression goes. His legs wobble and refuse to go any farther. The only hope for the runner is to keep his mind on the goal, on the victory to be won for himself and his team. It is that hope that keeps him going when every other part of his being wants to give up.

To the persecuted and discouraged believers at Thessalonica, Paul wrote words parallel to the thought here in Ephesians: “Since we are of the day, let us be sober, having put on the breastplate of faith and love, and as a helmet, the hope of salvation. For God has not destined us for wrath, but for obtaining salvation through our Lord Jesus Christ, who died for us, that whether we are awake or asleep, we may live together with Him. Therefore encourage one another, and build up one another, just as you also are doing” (1 Thess. 5:8–11).

To the worldly, fleshly Corinthians who were self–centered, divisive, and confused about the resurrection, Paul said, “If from human motives I fought with wild beasts at Ephesus, what does it profit Me? If the dead are not raised, let us eat and drink, for tomorrow we die” (1 Cor. 15:32). If the Christian has no future element of salvation to look forward to, if, as the apostle had said a few verses earlier, “we have hoped in Christ in this life only,” then “we are of all men most to be pitied” (v. 19). Paul’s own spiritual helmet was his firm hope in the completion of his salvation. “Momentary, light affliction is producing for us an eternal weight of glory far beyond all comparison, while we look not at the things which are seen, but at the things which are not seen; for the things which are seen are temporal, but the things which are not seen are eternal” (2 Cor. 4:17–18). The faithful believer does not “lose heart in doing good,” because he knows that “in due time we shall reap if we do not grow weary” (Gal. 6:9).

To the persecuted and beleaguered Christians to whom he wrote, Jude gave sobering warnings about false teachers, “ungodly persons who turn the grace of our God into licentiousness and deny our only Master and Lord, Jesus Christ” (v. 4). But he began the letter by addressing believers as “those who are the called, beloved in God the Father, and kept for Jesus Christ” (v. 1). Tereo (the verb behind “kept”) means to guard, keep watch over, and protect. God Himself guards, watches over, and protects every person who belongs to Him. Jude ended the letter by assuring believers that He “is able to keep you from stumbling, and to make you stand in the presence of His glory blameless with great joy” (v. 24; cf.a 1 Thess. 5:23). The word behind “keep” in this verse is not tereo, as in verse 1, but phulasso, which has the basic idea of securing in the midst of an attack. No matter what our spiritual enemies may throw against us, we are secured by God’s own power.

We sing of this assurance in Samuel Stone’s beloved hymn “The Church’s One Foundation”:

‘Mid toil and tribulation, and tumult of her war,

She waits the consummation of peace for evermore;

Till, with the vision glorious, her longing eyes are blest,

And the great church victorious shall be the church at rest.