Tim Keller on Spiritual warfare

10 Finally, be strong in the Lord and in His mighty power. 11 Put on the full armor of God, so that you can make your stand against the devil’s schemes. 12 For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this world’s darkness, and against the spiritual forces of evil in the heavenly realms. 13 Therefore take up the full armor of God, so that when the day of evil comes, you will be able to stand your ground, and having done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness arrayed, 15 and with your feet fitted with the readiness of the gospel of peace. 16 In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17 And take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 Pray in the Spirit at all times, with every kind of prayer and petition. To this end, stay alert with all perseverance in your prayers for all the saints.