Demons are not dumb. They are not illiterate. They are not unaware of a sovereign God. They are “intellectual believers” of who Jesus is. Just because demons cannot steal our salvation or bring any lasting harm to the Christian does not mean they are idiotic and lack real power.
For example, demons know that Christ is the Son of God (Mark 1:24-34; 3:11-12; 5:7). They knew that Paul and Silas were servants of God when Paul and Silas were imprisoned (Acts 16:17). When an exorcism was taking place in Acts 19, they resisted the name of Christ. Demons also believe that God is unified in the trinity (Jas 2:19).
Demons are very intelligent. You might even say, they are theologians (albeit false ones), but they understand some of the most basic Christian doctrines.
And this is one of the reasons demons are of concern. They know just enough truth to twist, distort and re-define God’s truth. Demons are “running around the world” promoting idolatry and errant religions (I Cor 10:14-21; I Tim 4:1). Demons are even likely having influence over a number of human governments around the world (Eph 6:12).
C.S. Lewis says,
“There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them.”
Demons are alive and well in our world today. What can or should we do about it?
First, if you know the Lord Jesus Christ, have no fear of them (I John 5:18). They cannot habitate or possess a Christian (II Co 6:15-16). There is no clear example in Scripture of a genuine believer ever being possessed by a demon.
Second, don’t think you have preeminent power over demons. Only Jesus has that authority. While you have examples of the apostles casting out demons in the N.T., that power did not originate with them, but it was bestowed upon them for a short time. The ability of a person to cast out demons (an example of performing miracles) ceased in the apostolic age.
Third, don’t assume anyone who is caught up in sin is demon possessed. In fact, the very last conclusion we should draw about anyone acting in an evil way is that they are demon possessed. No doubt, demon possession exists today, but it rarer than we realize.