In Ephesians 6:12, the apostle Paul writes to the churches of Asia Minor:
12 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. (ESV)
Who is your enemy in this life. Paul says it is not who we think. Paul says that those who are against us is not flesh and blood. That is it is no person who is your enemy, but something much darker, something much stronger, something that is spiritual and can not be seen.
I am always thinking that I am struggling against other humans, and if you watch any TV or go to the movies, the enemy usually are flesh and blood (with the exception of those who like the genres of science fiction and horror!). But in real life, I think that Paul speaks the truth. The real battle is against those forces behind the darkness in our lives. Forces that lead people to addictions, into immoral acts, into injustice and vile acts of cowardice and hatred.
But Paul does not think that this is the end of the story. He certainly thinks that we do not have power to defeat such darkness and spiritual evil. But Paul thinks that if we stand with the power of God around us, that our Creator, Sustenance, and Redeemer in Jesus Christ can and will destroy any evil we face:
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 firm. 14 Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, 15 and, as shoes for your feet, having put on the readiness given by the gospel of peace. 16 In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; 17 and take the helmet of salvation, and the sword of the Spirit, which is the word of God, 18 praying at all times in the Spirit, with all prayer and supplication. To that end keep alert with all perseverance, making supplication for all the saints. (ESV)