Satan exists and his aim is to attack Christians. Satan is the chief of demons. He is identified as the serpent of old, Satan (cf. Rev 12:9) who deceived Adam and Eve so that they took and ate from the tree of the knowledge of good and evil (Gen 3). Just as he deceived our first parents, he continues to deceive men today. Jesus told the religious leaders of his day, “You are of your father the devil, and your will is to do your father’s desires. He was a murderer from the beginning, and has nothing to do with the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies” (John 8:44). Satan is a murderer, a deceiver, and behind false religion.
Demons are fallen angels and share the same purpose as Satan, to attack and control men of the world for evil purposes. That this is true is illustrated by Jesus’ ministry of casting out demons (cf. Matt 8:16). Demons can control people against their desires (Matt 8:28–34) and even cause physical handicaps (Matt 9:32–33). These are only a selection of the many things demons can do in the world.
So should we worry? As Christians, do we need to fear being controlled by Satan and the demonic forces in the world? Some would answer yes to this question. They reason that demons can legitimately control Christians, which justifies the existence of so called deliverance ministries. One author explains of a Christian, “He thus becomes the victim of an enslavement from which he is unable to free himself without help in prayer.” Demons can, then, enslave believers according to Unger who further explains, “The demon enters, it is true, as a squatter and not as an owner or a guest or as one who has a right there.” Even if the demon is only a squatter, he still enters into a believer for the purpose of enslaving him.
However, the Bible teaches that Christians cannot be demon possessed. It teaches us that while demonic powers are a real force in the world, we have the tools to deal with them. After all, Jesus came into the world to conquer Satan (Heb 2:14) and is more powerful than any demonic power (Cf. 1 John 5:18).
Ephesians 6:10–20 explains that Christians have divine reconnaissance of the enemy, divine armor and divine weapons. When properly understood, this passage gives believers the tools needed to meet the enemy and overcome his schemes.
Over the next two weeks, a series of posts will explain how to stave off those pesky demons from Ephesians 6:10–20. Stay tuned.
*** NOTES ***
 Merrill Unger, What Demons Can Do to Saints (Chicago: Moody Press, 1977), 50.
Unger, Demons, 51.
Unger admits that the Holy Spirit indwells believers, but believes Demons and the Holy Spirit can live together. He reasons,
The claim that the Holy Spirit could not dwell in the same body with an evil spirit overlooks an important theological observation. It might with equal cogency be asked how the Holy Spirit can dwell in our bodies which are still possessed of the old nature and therefore subject to sin. Yet, He does because of our redemption and the presence of the new nature. (Demons, 51).
Of course, there is a difference between a principle of sin alive in a believer and a demon indwelling a believer. Unger appears to make a categorical mistake in equating a principle with a person.