According to Scripture, demon possession is a harsh reality. Though demons did enter and control people during biblical times, is it possible that it still happens today? The answer is yes. Demon possession and control did not end with the New Testament.
Symptoms
The symptoms of demon-possession today would be the same as in the New Testament era. These would include: superhuman strength, superhuman knowledge, a different voice speaking through the person, and the inability to control oneself.
Some Sicknesses
It is possible, at times, to find a correlation between sickness, mental illness, and demonic activity. Caution, however, must be exercised. It is not always possible for us to know the root cause of a particular sickness or mental illness. It is not Christlike, and it is very cruel, to attribute the suffering of a person to demonic activity. This may only add to their problems. The best thing to do is to pray for that person and ask the Lord to have His way with them - whatever the root of their problem may be.
Rule Out Other Possibilities
In so many instances where demon-possession is assumed, the problem turned out to be something else. Only after all other possibilities are exhausted, should demon-possession be considered as the root cause of their ordeal.
What To Do?
If demon-possession is suspected, it should not be treated lightly. The episode should be handled by spiritually mature people who are in Christian leadership, not by new believers. It is not something to be trifled with!
Can Be Set Free
Since demon-possession is a possibility, it is also possible for people to be controlled by God's Holy Spirit. The Lord Jesus came into the world to set people free from the power of evil, and place them under the control of the Holy Spirit of God.
The Return
Therefore, after a demon is exorcised, the Lord must come in and fill the void. Otherwise the last fate of the person will be worse than the first. Jesus warned about this.
When the unclean spirit has gone out of a person, it wanders through waterless regions looking for a resting place, but not finding any, it says, 'I will return to my house from which I came.' Then it goes and brings seven other spirits more evil than itself, and they enter and live there; and the last state of that person is worse than the first (Luke 11:24,26).
Controlled By The Lord
Those controlled by the Lord have God's Spirit indwelling them.
Jesus answered and said to him, "If anyone loves Me, he will keep My word; and My Father will love him, and We will come to him and make Our home with him (John 14:23).
Summary
Demon possession can still occur today. The symptoms would be similar as to those found in the New Testament. However one must be extremely careful when attributing unusual behavior to demon possession. There are other possibilities which should always be considered first.