Isn't the devil just an impersonal influence?
If that question is meant to imply that a personality called the devil does not actually exist, I must disagree. Satan does possess a sinister influence, but he is very much a real person. Over 200 times in the Bible direct reference is made to his personality. The name Satan is used 54 times. In Matthew 4:10 Jesus says, Get thee hence, Satan.
The Apostle Paul tells us in 2 Corinthians 11:14, Satan himself is transformed into an angel of light. This describes a personality.
The Apostle Peter, revealing the great anger and strength of the devil, declares him to be as a roaring lion (1 Pet. 5:8). This description certainly represents a personality.
John refers to the devil as the dragon (Rev. 20:2), describing his awful destruction upon humanity.
Jesus said of the devil in John 8:44: He ... abode not in the truth. It takes a personality to depart from the truth.
The devil is also called:
that Wicked (2 Thess. 2:8).
the god of this world (2 Cor. 4:4).
the tempter (1 Thess. 3:5).
the power of darkness (Col. 1:13).
your adversary (1 Pet. 5:8).
the accuser of our brethren (Rev. 12:10).
the prince of the devils (Matt. 12:24).
In James 4:7, we are told to resist the devil, and he will flee . . . .
These scriptures prove that there is indeed an evil personality who seeks to destroy all that God has made in this universe.
Is demon activity universal or local?
Demon power is universal. It may be found in any and every part of the world.
As I have mentioned before, the devil's power is stronger where there is no prayer and Bible reading. The reason for this is that Satan knows full well that he has no power to hurt people who plead the blood of Jesus as covering and who communicate with God in regular prayer.