God has supernatural opponents⤒🔗

They sacrificed to demons, which are not God — gods they had not known, gods that recently appeared, gods your fathers did not fear.Deuteronomy 32:17 

“Demon,” or “devil” as earlier translations rendered the words, is the Greek daimon and daimonion, the regular terms in the Gospels for the spiritual beings, corrupt and hostile to both God and man, whom Jesus exorcised from their victims in large numbers during his earthly ministry. The demons were fallen angels, deathless creatures serving Satan (Jesus equated Beelzebub, their reputed prince, with Satan: Matt. 12:24-29). Having joined Satan’s rebellion, they were cast out of heaven to await final judgment (2 Pet. 2:4; Jude 6). Their minds are permanently set to oppose God, goodness, truth, the kingdom of Christ, and the welfare of human beings, and they have real if limited power and freedom of movement, though in Calvin’s picturesque phrase they drag their chains wherever they go and can never hope to overcome God.

The level and intensity of demonic manifestations in people during Christ’s ministry was unique, having no parallel in Old Testament times or since; it was doubtless part of Satan’s desperate battle for his kingdom against Christ’s attack on it (Matt. 12:29). Demons were revealed as having knowledge and strength (Mark 1:24; 9:17-27). They inflicted, or at least exploited, physical and mental maladies (Mark 5:1-15; 9:17-18; Luke 11:14). They recognized and feared Christ, to whose authority they were subject (Mark 1:25; 3:11-12; 9:25), though by his own confession it was only through effort in prayer that he was able to expel them (Mark 9:29).

Christ authorized and equipped the Twelve and the seventy to exorcise in his name (i.e., by his power — Luke 9:1; 10:17), and the ministry of exorcism continues still as an occasional pastoral necessity. The sixteenth-century Lutheran church abolished exorcism, believing that Christ’s victory over Satan had suppressed demonic invasion forever, but this was premature.

Satan’s army of demons uses subtler strategies also, namely, deception and discouragement in many forms. Opposing these is the essence of spiritual warfare (Eph. 6:10-18). Though demons can give trouble of many kinds to regenerate persons in whom the Holy Spirit dwells, they cannot finally thwart God’s purpose of saving his elect any more than they can finally avoid their own eternal torment. As the devil is God’s devil (that is Luther’s phrase), so the demons are God’s demons, defeated enemies (Col. 2:15) whose limited power is prolonged only for the advancement of God’s glory as his people contend with them.