He put on righteousness as a breastplate, and a helmet of salvation on his head; he put on garments of vengeance for clothing, and wrapped himself in zeal as a cloak.
3 For though we walk in the flesh, we are not waging war according to the flesh. 4 For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. 5 We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ, 6 being ready to punish every disobedience, when your obedience is complete.
—2 Corinthians 10:3-6
A scriptural basis for the concept of spiritual warfare is found in the Epistle to the Ephesians, where Paul of Tarsus metaphorically arms the Christian with weapons and armor that recall those of a Roman centurion:
“ 10 Finally, be strong in the Lord and in his mighty power. 11 Put on the full armor of God so that you can take 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 dark world and against the spiritual forces of evil in the heavenly realms. 13 Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15 and with your feet fitted with the readiness that comes from 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 Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints.
Major traditions of Western Christianity — including Roman Catholic, Anglican, and Protestant — acknowledge a belief in the reality (or ontological existence) of a fallen angel known as the Devil and Satan. This affirmation is reinforced in the writings of the Early Church Fathers, in the Councils and Creeds of the early Church, and in the later confessional documents of some Christian denominations.
The doctrinal position of some Western Christian Church traditions is that Satan and other fallen angels, or demons, are spiritual entities that exist and sometimes manifest their presence in the world. These entities exist to deceive humanity. Their primary mission is to thwart God's purposes on earth, and to prevent non-believers from placing faith in Christ and to prevent Christians from being effective disciples of Yeshua (Jesus). Satan is referred to as "the father of lies" (John 8:44) and as "the accuser of our brothers" (Revelation 12:10).
War John Piper Sermon Jam,
Underground Church Preparations interview with Chuck Missler.