In my final semester of seminary, I enrolled in a class named "Spiritual Warfare in Ministry and Mission" -- or, as we all called it, Defense Against the Dark Arts. (Seminary is kind of like Hogwarts.) The class focused on the realities of the darker dimension of the spiritual realm: demons, possession, demonization, curses, witchcraft, deliverance, exorcism, things of that nature. To even teach such things requires a starting premise: we accept it as true, as real.
Somewhere along the way, that assumption was lost to Western Christians -- and the rest of our culture. Demons became good fodder for horror movies and little else. No truly enlightened, intelligent individual could possibly believe magic exists. Even Satan himself was turned into a concept, the personification of human evil, not a fallen, malevolent archangel.
The problem is, the Bible treats them all as real. Sorcerers, witches, and mediums abound. A literal Satan is encountered, as are demons beyond measure. Paul tells the Christians in Ephesus to put on the whole armor of God, not because evil is abstract, but because of the reality of spiritual warfare, because Satan is armed with flaming arrows and never grows tired of the hunt.
Spiritual warfare is a daily struggle. We live in a battleground; our universe is at war, the cosmic forces of good and evil each seeking to gain territory until the last trumpet sounds and God inevitably wins the last battle. Fortunately for us, Christ has already won the war for us. His triumph on the cross provides a way for each of us to share in the final victory, to defeat death, hell, and sin through salvation and eternal life -- and that's good news!