Christian believers by the blood of Jesus Christ are protected from demonic possession. However, we may still be demonically oppressed and/or hindered. Paul the apostle wrote of his ministry being hindered by Satan in 1 Thessalonians 2:17-18, "But since we were torn away from you, brothers, for a short time, in person not in heart, we endeavored the more eagerly and with great desire to see you face to face, because we wanted to come to you--I, Paul, again and again--but Satan hindered us." Unbelievers are completely unprotected and in severe instances may suffer demonic possession. In this article I will mainly address causes of demonic oppression for believers which could lead in extreme cases lead to possession in unbelievers.
Besides being hindered in our Christian walk and ministry we may also be demonically oppressed through mental anguish or turmoil, fear and anxiety, financial problems, illnesses, despondency and depression, etc... As Christians it is a fact that Satan and his demons will do all they can to hinder and oppress us at every turn and opportunity. I have experienced this personally in my own walk and especially in ministry.
So what might expose us to demonic oppression? What tools does Satan use in an effort to sway us from the path leading to the narrow gate (Matthew 7:13)? His ways are usually much more sinister and subtle than that of the raging demons portrayed in modern films. Some of Satan's most brilliant deceptions may even appear to be of God for those without Biblical grounding and discernment.
And no wonder, for even Satan disguises himself as an angel of light. So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds. - 2 Corinthians 11:14-15
So what are some of the causes that could potentially expose a believer to demonic oppression and an unbeliever to demonic possession?
Obviously anything to do with the occult.
Occult meditation methods
Pornography is the sin of lust which may invite demonic activity.
Involvement with false religions such as Mormonism, New Age Spiritualism, Jehovah's Witnesses, Roman Catholicism, Alcoholics Anonymous, etc... which are the doctrines of demons.
Now the Spirit expressly says that in later times some will depart from the faith by devoting themselves to deceitful spirits and teachings of demons, - 1 Timothy 4:1
Drug use - which I would like to expand on a bit as both legal and illegal drug use, reliance, and addiction are rapidly increasing in modern society.
We are commanded in scripture to be sober minded (1 Peter 4:7). Yet, drug use leads directly to the mind being out of control and into varying degrees of altered states. Also, consider that the Greek word for sorcery is "Pharmakia" from which the English word pharmaceutical derives. So from a Biblical perspective I think it is fair to conclude that mind and/or mood altering pharmaceuticals could very well be considered a form of sorcery. (See Galatians 5:19-21 and Revelation 9:20-21)
Now let's take this a little further and consider the modern obsession with psych meds from Satan's perspective. Because so often, when a sinner hears the gospel and begins to experience conviction of sin, they may go through a period of struggle and depression which may very well need to happen for them to come into the truth of and faith in Jesus Christ. Yet, in modern society - especially in America, the person suffering from even the slightest depression or mental struggle is quickly "diagnosed", drugged, and led into secular remedies and programs which nearly always fail and lead away from the gospel and salvation in Jesus Christ and instead to eternal destruction. The demonic influence was just subtle and insistent enough to lead the sinner from the truth of the Word and into a state of oppression, spiritual darkness and possibly possession.
There is a grief that all sinners must experience when faced with the truth of their sin that will lead them into repentance and faith in Jesus Christ. The last thing Satan wants is for that to happen and he is a master at using pharmakia, schemes, and false teachings to lead souls from the truth.
For godly grief produces a repentance that leads to salvation without regret, whereas worldly grief produces death. - 2 Corinthians 7:10
For believers, we must understand the danger of relying on drugs - especially for "psychological" or emotional issues instead of going to the Lord in prayer and the study of His Word. It may very well be that a period of depression or struggle may be a blessing in disguise intended to draw us closer to Christ. If we do not seek the Lord in times of anguish but instead turn to psych meds we may very well be opening ourselves up to demonic oppression.
Am I claiming that Christians should never use legal psychiatric drugs for any reason whatsoever? No I am not. However, I think it is very clear that there is an epidemic of reliance on these drugs that is far beyond any measure of sense. They should be a very last resort in obviously severe situations.
The point I am hoping to make to Christian believers is that we must put our faith, trust, and reliance in Jesus Christ before and above all else and with all that we are. There is nothing that our Savior cannot deliver us from regardless of how much society in this fallen and lost world strives to convince us otherwise.
Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect. - Romans 12:2