Possession vs. Oppression
Possession
It is important to define our terms if we are going to understand any subject. So, I want to define what I mean by the term "being possessed" by something. Possession can simply mean being affected or influenced by something (like being "possessed with a thought or idea), but when I mention "demon possession," I am referring to cases where a demonic spirit actually enters into the person and takes control over that person's actions.
One can sort of understand this If they have ever heard of parasites that take over a host and cause them to do crazy things such as drowning themselves in a body of water, like the grasshopper does after a "hairworm" enters its body. There are plenty of other examples such as a certain type of tape worm that cause it's host, a tiny fish, to swim into warmer water where the parasite can breed. With a little research, one can find many of such examples which I feel illustrate the type of possession that happens when a demon enters a host.
It will be tough to sort through all the examples of demon "possession" in the Bible because many examples are vague. For instance, Mark 1:32 mentions those who were "possessed with devils" but doesn't give any information beyond that. Also, there are some cases mentioned of people having an "evil spirit" or such, which I will address later. This could be simply a "bad mood" or emotion, but doesn't seem to be related to demon "possession" at all. There are a few specific examples, however, that show us how a person behaved when actually possessed by demons. Following are a few examples:
-In Matthew 8 there are 2 men possessed with many demons. They are said to have hung out in a tomb and were very fierce (salvage and dangerous). The demons apparently spoke audibly to Jesus through one or both of the possessed men.
-Mark 5 tells more about one of the above mentioned men who could not be bound with chains and fetters. He also cried and cut himself.
-In this same story, the demons enter into a herd of swine and cause the swine to run quickly into the sea and die.
-Matthew 12 tells of someone who was possessed that was not able to see or talk ("blind and dumb")
There is no indication that the above mentioned people were saved at the time they were possessed. In Jesus' presence, and by His word, however, the demons were certainly cast out. They were even afraid of Jesus as we see in the legion of demons that were cast into the swine.
Some would say that Judas was demon possessed. According to Luke 22, Judas was apparently possessed by Satan himself. However, as I will point out later, Satan can lead people to do things without actually "possessing" them. A more important question here is "Was Judas 'saved?'" I believe he was not ( see John 13:10,11 and John 17:12). Therefore, Judas is excluded from this list anyway.
Oppression
Sometimes, there is no reference to a person actually being "possessed," yet they are certainly influenced by Satan or he causes them harm in some manner. I would call this "Oppression." There are several examples of this happening to "saints" (the "righteous" in the Old Testament or those who are "saved" in the New Testament) Here are some examples:
-Job (Job 1 and 2). Satan had part in the murder of Job's servants. He also had part in the "great wind" that killed Job's children. Finally, he had part in the boils that plagued Job all over his body. Notice that in none of these cases did Satan actually control Job's actions. Job had total control over how he reacted to each incident. Notice also that Satan wasn't able to do any of these things without God's permission. This is important.
-Saul (1 Sam. 16:14, also in chapter 18 and 19). Saul was overtaken by an "evil spirit." However, it is clear in every instance that the "spirit" comes from the Lord. What exactly that is, whether it is a "bad mood" or "unrest," or something else is another matter, but it is clearly not demon possession.
-Peter (Mark 8:32). Jesus, in conversation with Peter, rebukes Satan. This may appear as though Satan was in Peter at the time, but it is certainly not proof that Satan, or a demon, possessed Peter. It shows us only that either Satan was at work in what Peter was saying or that Peter was simply acting as Satan would.
So, we have to be careful when we talk of "demon possession" that we are actually talking about a demon "entering" and "taking over" a person's actions. Often, when a case is submitted for consideration, it seems to be more "oppression," or just someone willing to do something that resembles the work of Satan. These are not cases where a demon or "spirit" actually enters and controls a person.
Spirits and Demons
We also need to define a couple terms regarding "spirits" and "demons." Whether one believes a Christian can be demon possessed or not may depend on a proper understanding of these terms. Whereas I won't cover a whole lot of details regarding Demonology (study of demons) or Pneumatology (study of spiritual beings), I do want to point out a few things on the subject.
First, I would like to address briefly what a demon is not. Some refer to physical or psychological conditions as "demons," but that is a misunderstanding. I have heard reference to the "Demon of anger," the "Demon of alcoholism," or the "Demon of depression." However, I find no evidence for anything like this in scripture. These are simply the works of our own flesh in which we live. According to Galatians 5: 19-21, the "works of the flesh" are: Adultery, fornication (sexual sins), uncleanness, lasciviousness (given to lustful desires), idolatry, witchcraft, hatred, variance (contention), emulations (jealousy), wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings (being drunk). (Parenthesis mine). You can see in this list nothing about demons, but rather they are the works that we allow of our own choice. Too often we blame thing on "demons" which are actually our own doing.
Now, without going to great lengths, I will attempt to give a brief description of what a "demon" is. A demon, or "devil" as they are often referred to as in the scriptures, is a spirit. A spirit simply means they are beings that consist of a material we do not acknowledge. They are invisible to us (sort of like wind). Jesus says in John 4:24 that God the Father is a spirit. As such, the Bible says on several occasions that no man has seen God. In some cases, He is explained as "Light." We also apparently are born with a spiritual part to us that we cannot see or comprehend, but it will continue to exist after the bodies that we are in are gone.
At some point, in "the beginning," spiritual beings were made by God (Psalm 148:1-5). There appears to be different ranks of these spirits (Colossians 1:16, Ephesians 1:21, 6:12). The Bible mentions "archangels," "seraphim," "cherubim," and "angels." Satan, who is referred to as Lucifer ("light bearer," "shining one," "morning star") was apparently a cherub (Ezekiel 28:14) who had a free will and chose in pride to rebel against God (Isaiah 14:12-14, Ezekiel 28:12-18, Luke 10:18). A certain number of angels were apparently cast out of Heaven with him (Revelation 12:9). It is widely believed that these fallen angels are the "demons" that roam around the Earth under Satan's leadership. Their destiny is eternal damnation (Daniel 8:10, Matthew 25:41, 2 Peter 2:4)
There is no doubt that Christians deal with these unseen forces on a regular basis. Ephesians 6:12 says "For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." It is also clear in scripture that we are too weak to be able to prevail against this power on our own. The important thing to understand though, is the power that we have in the Lord as His children.
The Holy Spirit and the Child of God
Perhaps most important to this subject, we must understand the Holy Spirit's role in the life of a Christian. Jesus told the disciples that when He was gone he would send the Comforter, the Holy Ghost (John 14:16, 14:26). In the book of Acts, we see the Holy Ghost ascending down upon the disciples in a special way (Acts 2:1,2). From that point on, the Holy Spirit is said to be received by everyone who accepts Christ as their Savior. Upon receiving Christ, a "born-again" Christian is "sealed" with the Holy Spirit (John 6:27, 2 Cor. 1:21,22, Eph 1:13, Eph 4:30). Our bodies become the "temple" of the Holy Spirit (1 Cor. 6:19, 2 Cor. 6:16). This is great news for us!
Satan does want to destroy the children of God. 1 Peter 5:8 tells us to "Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour." We are warned of his damaging power, and we are told that we are in a spiritual battle against Satan and the powers of evil (Eph. 6:12) We need to do our best not to let the powers of evil influence us to do damage to the Kingdom of God.
However, I believe scripture is clear that Satan has certain limitations. One of his limitations seems to be that he cannot control a born-again Christian beyond what we allow. More importantly though, he cannot do anything God the Father does not allow him to do. Therefore, I do not believe there is any reason to worry about Satan possessing us if we have been born-again, and as long as we are walking in the Spirit (which indwells us), we will not be "oppressed" by Satan either. Satan is dangerous, and his powers are great, but the Bible tells us in 1 John 4:4 "Greater is He that is in us."