Enemy-occupied territory—that is what this world is. Christianity is the story of how the rightful king has landed, you might say landed in disguise, and is calling us to take part in a great campaign of sabotage.
― C.S. Lewis, Mere Christianity
There is warfare because the rest of the planet is unredeemed from slavery. There’s a war on against slavery. When Israelites were slaves in Egypt they were not at war as they were not trusted to be at war, but when they reached the promised land they had their battles. Before we were Christians we had nothing to do with warfare, but now we are redeemed we have all kinds of battles.
For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. Therefore take up the whole armour of God, that you may be able to withstand in the evil day, and having done all, to stand firm.
The battle is not to be taken lightly. This is the war, whatever other wars may happen. We are not fighting against people or anything else we can see, but against evil forces whose plan is to bring down the church.
But God’s plan is going on behind this. Notice that it is not about fighting in this warfare, but about standing. This is because 2,000 years ago Jesus said, “It is finished.” We stand in what he has achieved on the cross.
Hebrews 12:1 says “Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us.” So there are two things we must do in this warfare: stand firm and run the race.