The depiction of the armor of God in Ephesians (6:10-19) is often taken as a colorful illustration, which makes for great sermonizing, but is not usually considered as central to the gospel. Defeat of the powers and personal engagement in this defeat, to say nothing of the notion that Christ came to defeat evil, are often displaced by theories of the atonement focused on deliverance from the wrath of God, and limited to a legal remedy of imputed righteousness, none of which allows for primary focus on personal engagement with and defeat of evil. In this understanding, the gospel is thought to pertain to more effervescent and transcendent categories rather than depicting how it weaponizes those who bear it and wear it with a capacity to engage and defeat evil. Thus, what the early church and Paul considered the very heart of salvation is dismissed as a fun allegory, more suited to children’s choruses than serious theologizing. How this came to be is largely explained by the Constantinian shift.
Constantinianism is a form of Christianity which has abandoned Christ’s strategy for what it presumes is a more effective method. As Nathan Kerr describes it:
Constantinianism most fundamentally names a certain orientation toward the political meaning of history which is rooted in a heretical eschatology based upon a misconception of the relation of Christ to history. Most importantly, Constantinianism proceeds as if what happened in the cross, resurrection, and ascension of Jesus had not profoundly altered history, and it provides for the church a way of acting politically in history which is not entirely determined by the lordship of Jesus Christ.
According to John Howard Yoder, Constantinianism (true to the vision of Constantine), moves the sign of the cross from Golgotha to the battlefield, and conquering under this sign no longer entails taking up the cross as an instrument of self-giving sacrifice but it reinforces sacrificing one’s enemies in violence and warfare. As Jordan Wood describes, Yoder “is not merely claiming that ‘Constantinianism’ tempts Christians to disobey the commands of Jesus, but that it tempts them to renounce their destiny to be like God.” In Yoder’s estimate this temptation becomes reality in the undoing of the church/world distinction, such that the church disappears and the Roman State takes its place:
Before Constantine, one knew as a fact of everyday experience that there was a believing Christian community but one had to “take it on faith” that God was governing history. After Constantine, one had to believe without seeing that there was a community of believers, within the larger nominally Christian mass, but one knew for a fact that God was in control of history.
Prior to Constantine the persecuted and martyred Christians marked the church state distinction, but with the Constantinian embrace of Christianity, all Romans were (mostly) Christian and the church became an indistinct part of the masses, while Rome’s rule in the name of Christ was interpreted as the arrival of the kingdom. Thus, every Roman soldier was required to be a Christian, and soldiering for Christ was sublated by literal killing and service to the State. This ideology persists in Christendom, such that Paul’s illustration is often allegorized and spiritualized away.
Four key points need to be made regarding the gospel armor in Ephesians 6 to regain the meaning and centrality of this passage:
1. If Ephesians is, as I have argued (along with the early church fathers such as Origen, and contemporary scholars such as Douglas Campbell – here) the center and summary of Paul’s gospel, then Ephesians 6 as a summary of all that Paul has said in Ephesians, encapsulates Paul’s understanding of how the gospel works to defeat evil and bring about salvation (as I demonstrate below). As Joshua Greever notes, Romans 13:12–14 is a parallel text, in which Paul urges Christians to “put on the armor of light” (13:12), but then follows this up in 13:14 with “put on the Lord Jesus Christ,” “suggesting that putting on the armor of light is nothing other than putting on the Lord Jesus.” In other words, by encouraging them to put on this armor Paul is urging them once again to “put on Christ” and is summarizing his gospel with the added urgency to do this and thus defeat the powers.
2. Paul’s gospel is built upon resistance to evil. The genius of Walter Wink is in recognizing (and one could point to the failure of theologians such as David Hart and John Milbank, who both eloquently describe a peaceful ontology but fail to recognize) what Wink calls the third way of the gospel. This third way is not nonresistance or violent resistance to evil, but nonviolent resistance to evil. As Wink writes, “Jesus is not telling us to submit to evil, but to refuse to oppose it on its own terms. We are not to let the opponent dictate the methods of our opposition. He is urging us to transcend both passivity and violence by finding a third way, one that is at once assertive and yet nonviolent.” Christ does not promote passive resistance or violent resistance, but Christ offers the singular solution – the gospel.
3. In Ephesians 6:10-19, Paul is describing salvation. Salvation defeats evil in the form of the powers of this world and the only way these powers are defeated is through the means provided by God. Taking Ephesians as a whole and Ephesians six, in particular, as descriptive of salvation, means salvation is not deliverance from God but deliverance from the cosmic powers of evil, death, and the devil. The captivating power, the darkening power, the death dealing power, is not the power of God but the rulers, the authorities, the cosmic powers (the cosmocrats), the spiritual forces of evil in the heavenly places (6:12). The cosmic struggle is not removed from the historical, political, and earthly, and so too, the Christian engages these spiritual forces through their earthly manifestations. Ideologies and institutions manifesting the various forms of individual and corporate violence and oppression (e.g., nationalism, fascism, racism, sexism, legalism) constitute the cosmos of darkness. There is no mystery as to the power of evil (this power of death and violence is the coin of the realm of the kingdoms of darkness) undone by the gospel of peace, truth, and righteousness.
That the mode of this salvation is provided by God is made clear in the armor passages Paul is echoing. The description of God’s armor in Isaiah (which Paul must be following) and God’s saving is Israel’s only hope: “And He saw that there was no man, And was astonished that there was no one to intercede;Then His own arm brought salvation to Him, And His righteousness upheld Him” (Is 59:16). God alone can accomplish this salvation and he alone has this armor.
Why can only God save? The obvious answer is in Paul’s depiction of the power of God (equated at 6:10 ff. with the armor) found (as he has explained) in Christ’s resurrection, ascension, and reign over the powers:
what is the surpassing greatness of His power toward us who believe. These are in accordance with the working of the strength of His might which He brought about in Christ, when He raised Him from the dead and seated Him at His right hand in the heavenly places, far above all rule and authority and power and dominion (Eph 1:19–21).
Paul has explained the strength of the Lord and how believers appropriate this strength, thus his command to “be strong in the Lord and in the strength of His might” (6:10) is a reiteration of the opening of the letter. It is through the gospel that God in Christ defeats death, and the powers that depend upon death. Christ is seated at the Father’s right hand in the heavenly place and this exaltation of Christ implies the disarming of all cosmic powers, and this disarming power is to be appropriated by each Christian.
4. Salvation involves a real-world defeat of the principalities and powers in the life of the believer. There is simultaneously the corporate empowerment (implying an army), but the focus in this passage is on the individual soldier. To state it most succinctly: to be saved is to be saved from the powers as outlined in the armor passage. This is inclusive of the thought (head), action (feet), and heart (breast) of the individual. The armor weaponizes the individual against the “fiery darts of the evil one” by creating a new plan of action (feet shod with the gospel of peace), a new world of thought (the head and mind transformed by the helmet of salvation), and a new ethic and worldview (the breast plate of righteousness and the belt of truth girding up the whole outfit). Defeating the powers, though it may not be a full explanation of salvation, is synonymous or at least synchronous with salvation in that the fulness of the gospel is required (with all of its positive benefits) to counteract, as Ephesians puts it, “the flaming arrows of the evil one” (Eph. 6:16).
Paul’s picture of salvation through the defeat of the powers focuses on the perspective of the individual soldier. This soldier has the resources of his Lord seated at the right hand of God, but he only sees the battle in the limited perspective of one directly engaged in warfare. It is only the commander on high who can survey the entire field of battle and he alone understands how this battle is to be won. One must trust that God is in control of history, as only the immediate warfare is in plain sight. The temptation is to judge this methodology ineffective and to replace the armor and weaponry of the gospel with the sword of state. The kenotic self-sacrificing power of the cross, the feet shod with the gospel of peace, the head protected by salvation, are unlikely strategies for victory by the standards of worldly power, so the soldier must have faith in his weapons and his commander or abandon the gospel. The final outcome is assured only in the eschaton.
 Nathan R. Kerr, Christ, History and Apocalyptic: The Politics of Christian Mission (Eugene: Cascade, 2009) 7. Quoted in Jordan Wood, Assessing the “Constantinian Shift”: A Defense of the Theological Question, Presented at “For the Good of the Many”: Constantine and the Edict of Milan on Its 1700th Anniversary St. Louis, September 20, 2013.
 The description is from John Howard Yoder, “The Constantinian Sources of Western Social Ethics,” in The Priestly Kingdom: Social Ethics Gospel (Notre Dame: University of Notre Dame Press, 1984): 145. Quoted by Wood, 7.
 Wood, 7.
 Yoder, “The Constantinian Sources,” 137. Quoted in Wood, 4.
 Throughout his description of the armor, Paul is appealing to his former key points (a few examples must suffice): “the strength of his might” of 6:10 is defined by resurrection and ascension at 1:19; “put on the whole armor of God” has its parallel explanation at 4:24, “put on the new self”; “the schemes of the devil” (6:11) are explained at 4:14 as “deceitful schemes” and the Ephesians are warned “give no opportunity to the devil” at 4:27; the first three pieces of armor—peace, truth and righteousness (6:13-15) are defined earlier by Christ. Truth is directly equated with Jesus (4:21), and truth and righteousness are found in the one new man created and embodied in Christ (4:24; cf. 2:15), and the original preacher and resource of the gospel of peace is Jesus (2:17); the defeat of the rulers and authorities of 6:12 has been explained at 1:21, as Christ (resurrected and ascended) is far above all rule and authority and power and dominion, inclusive at 2:2 of the authoritative ruler of the air and at 3:10 the manifold wisdom of God might now be made known to the rulers and authorities in the heavenly places. For an exhaustive list Joshua M. Greever, The Armor of God, the Gospel of Christ, and Standing Firm against the ‘Powers’ (Ephesians 6:10–20); [JBTS 5.1 (2020): 72–89].
 Ibid, 84.
 Walter Wink, The Powers That Be (p. 101). Potter/Ten Speed/Harmony/Rodale. Kindle Edition.