I want to say a vigorous and unrepentant “Yes” to that image!
First, though, a clarification or two. I do NOT have in mind actual military conflict or the use of weapons in any fashion. I'm a pacifist and I believe the church should be too. Nor do I mean the strident, angry, mean-spirited culture war type of warfare. Both of these types of conflict are antithetical to participation in God's mission in the world.
Yet . . . we are in a war! A war whose decisive and climactic battle has already been won. Our D-Day happened on Calvary around 30 A.D. We live now in aftermath of Christ's cross and resurrection awaiting V-Day when Christ returns to finally and fully establish God's kingdom. Our job is to witness to his victory and authenticate it by our life together as a sign, sacrament, and servant of that coming kingdom.
The powers Christ dealt with are “disarmed” (Col.2:15) and his enemies “defeated” (1 Cor.15:54-57). These enemies are not yet “destroyed” however (1 Cor.15:26), nor the powers fully pacified. That's why, like the Allied forces between D-Day and V-Day, our calling as the church is engage the remaining resistance of our defeated and disarmed foes with declarations an demonstrations of the truth of the gospel which unveils the defeat of “sin, death, and the (d)evil” and shows the powers their reign of distorting the conditions for human life and flourishing is at an end (Eph.3:10).
Our goal is to free humanity from their bondage to the lies and illusions these enemies and powers keep assaulting them with. That's really all they can do – keep luring us to embrace their lies and illusions and continue to live as if Jesus has not won the victory. Karl Barth sets us straight on this.
“The Easter message tells us that our enemies, sin, the curse and death, are beaten. Ultimately they can no longer start mischief. They still behave as though the game were not decided, the battle not fought; we must still reckon with them, but fundamentally we must cease to fear them any more. If you have heard the Easter message, you can no longer run around with a tragic face and lead the humorless existence of a man who has no hope. One thing still holds, and only this one thing is really serious, that Jesus is the Victor.” (Dogmatics in Outline, 123)
In fact, in living free of the lies and illusions God's enemies and the powers use enable us to show others in word and deed that all of us apart from Christ have common suprahuman enemies that keep us locked into the tragic and deadly antagonisms and arrangements that plague our world. Our human oppressor or enemy is not the enemy we must confront. Instead, the church is called find potential friends in strangers and enemies. We treat them thus even if they do us hurt or betrayal. This is how we declare and demonstrate that the power of sin, death, and the (d)evil are in truth defeated and the powers of distortion and disruption of God's good order put on notice that their days are numbered.
In fact, in living free of the enemies and powers that have opposed God in every age and epoch is “the” chief task of God's people. Whether as families, wandering nomads, a nation united, a nation divided, a people in exile, a people living under foreign overlords in their own land, a church spread throughout the earth, in all these forms God's people are supposed to be what I think can best be called God's Subversive, Counter-Revolutionary Movement.
Subversive because we infiltrate and seek change person by person, situation by situation, person to person. We have no grand scheme by which to organize the world for God from the top own. The most highly-exalted One did his redeeming work this way, and so must his people.
Counter-Revolutionary, even though this is usually a negative terms for us Enlightenment liberals, because we set ourselves against the attitudes, actions, patterns, and structures written into the fabric of “the way things are” by the history of sinful humanity (sin being the original revolution away from God). The twist to this way of being counter-revolutionary is that we live from the way the world will be not the way it is or has been.
Israel never quite lived out this calling. But Jesus Christ did. As the one faithful Israelite he gathered and still gathers around him all who follow him empowering them with the Spirit and the gifts necessary for our continuing warfare.
The letter to the Ephesians give us scriptural warrant to think of our service to Christ in military terms. Tim Gombis has shown how Paul uses the Divine Warfare pattern to structure the letter as a call to service in God's ongoing struggle in and with the world. Andrew Lincoln has demonstrated that the rhetoric of the letter points us to the familiar “full armor of God” passage in ch.6 as Paul's climax and “point” in writing. And Thomas Yoder Neufeld has helpfully recovered the insight that the armor we are to take up is not just that of the Roman soldier of Paul's time but rather God's own armor he wore to do battle with his enemies and recalcitrant people in the Old Testament. Together, all these insights make it inescapable that Ephesians gives us a hermeneutically responsible reflection on the use of military imagery for a non-violent church.
The virtues of such a model are the direction, urgency, intentionality, and bodily-ness it gives to our following Christ. It takes these matters and more to be effective soldiers. It takes no less for the church to be God's Subversive Counter-Revolutionary people. A people trained, equipped, and focused on seeking God's shalom as they “Lift High the Cross” and bear it daily into the nitty-gritty of daily life – that would be a church that others may still reject. But they would be rejecting it for the right reasons not the many matters we speculate today cause people to become “Nones” and “Dones” with regard to the church!
That's why we are indeed in a war. And why it matters that we know and participate in God's Subversive Counter-Revolutionary movement. God wants it. In living it out we discover our true humanity. And the world beholds its own destiny.