In understanding God’s dealings with men, we must see that Jesus Christ is the fulcrum of history. His life, death, resurrection, ascension and exaltation as Lord changed a number of things relative to the way in which God dealt with mankind. One thing that did not change from the Old Testament to the New Testament is that God never does evil, nor does He send suffering to those who love Him.
The New Testament is very clear that the Devil, not God, is the source of evil and of much human suffering. For example, it is the Devil who holds the power of death, which God specifically calls an “enemy” (1 Cor. 15:26).
Since the children have flesh and blood, he too shared in their humanity so that by his death he might destroy him who holds the power of death— that is, the devil.
The Devil, not God, comes to steal, kill, and destroy.
The thief comes only to steal and kill and destroy; I have come that they may have life, and have it to the full.
The Devil oppresses people, but God and His Son do only good.
How God anointed Jesus of Nazareth with the Holy Spirit and power, and how he went around doing good and healing all who were under the power of the devil, because God was with him.
Jesus Christ came to destroy the work of the Devil.
1 John 3:8
He who does what is sinful is of the devil, because the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the devil’s work.
Please read 1 John 3:8 again very carefully, because it contains a great truth. There are many Christians who will readily admit that the sickness and death so widespread on the earth today is indeed “the Devil’s work.” However, many also say, as did John Calvin, that the Devil could not do any of it unless God allowed him to.  This turns God into a “godfather,” directing criminal activity at His will, and it ignores the first part of 1 John 3:8, which says the Devil has been sinning from the beginning. If he has been doing the will of God, he has not been “sinning.” Only if he is doing things that God does not want him doing can he be said to be “sinning.”
A cursory reading of the Bible seems to indicate a big change in God between the Old and New Testaments. This cannot be the case, however, because God does not change (Mal. 3:6). Neither does He ever contradict Himself. Both the Old and New Testaments are “God-breathed” (2 Tim. 3:16), and therefore must be perfectly harmonious. Let us now note some things that seem to be contradictions, and then we will show why they are not and how they are biblically reconciled.
The Old Testament seems to make God the cause of disease, destruction, and death. The New Testament attributes these things to the Devil. The Old Testament portrays God as the ruler of the world, in charge of both good and evil, and that is what the Hebrew people believed. Job said, “Shall we accept good from God, and not trouble?” (Job 2:10). The New Testament, however, paints a different picture: the Devil is “the god of this age” (2 Cor. 4:4). It is he who controls much of what is going on in the world, it is he who offered all the world’s power and glory to Jesus (Matt. 4:8, Luke 4:5 and 6). In the Old Testament, God is portrayed as the cause of good and bad. In the New Testament, the Devil causes evil (John 10:10a), but God sends “every good and perfect gift” (James 1:17).
In the Old Testament, the Hebrew people recognized the existence of a spirit realm. They knew that some spirits did horrible things, but believed they were sent by God to do His work. Thus King Saul’s attendants said to him, “See, an evil spirit from God is tormenting you” (1 Sam. 16:15). Nowhere is there set forth the truth about two spiritual kingdoms at war with each other. Nowhere in the Old Testament is anyone told to cast out an evil spirit. Rather, God told the people of Israel to kill certain people who opposed them. The spiritual battle was manifest in the physical realm. But in the New Testament we clearly see the battle between God’s spiritual forces and the Devil’s army of evil spirits. Rather than kill people, Jesus cast out many of these evil spirits from them. Here are a few examples:
When evening came, many who were demon-possessed were brought to him, and he drove out the spirits with a word and healed all the sick.
And Jesus healed many who had various diseases. He also drove out many demons, but he would not let the demons speak because they knew who he was.
When Jesus rose early on the first day of the week, he appeared first to Mary Magdalene, out of whom he had driven seven demons.
Luke 11:14, 15, 17, and 18
(14) Jesus was driving out a demon that was mute, when the demon left, the man who had been mute spoke, and the crowd was amazed.
(15) But some of them said, “By Beelzebub, the prince of demons, he is driving out demons.”
(17) Jesus knew their thoughts and said to them: “Any kingdom divided against itself will be ruined, and a house divided against itself will fall.”
(18) If Satan is divided against himself, how can his kingdom stand? I say this because you claim that I drive out demons by Beelzebub.
The above record in Luke is very telling. Some in the crowd accused Jesus of casting out devils with devils. Jesus’ answer was that a kingdom divided against itself cannot stand. This logic certainly holds true for God’s kingdom also. God is not pitting His own forces against one another. He does not allow a person to become possessed by devils (with all the horrors to one’s life, family and friends that can accompany such possession) and then later cast out the devils He allowed in. If He did, and if Jesus’ logic is correct, His (God’s) kingdom would not stand.
Not only did Jesus himself cast out evil spirits, but he also equipped his disciples with power over evil spirits.
Mark 3:14 and 15
(14) He appointed twelve — designating them apostles — that they might be with him
(15) And that he might send them out to preach and to have authority to drive out demons.
The seventy-two returned with joy and said, “Lord, even the demons submit to us in your name.”
We submit that of all the awesome men and women of God whose exploits are chronicled in the Old Testament, not one of them said anything like the above statement made by the disciples.
(18) He replied, “ I saw Satan fall like lightning from heaven.
(19) I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy; nothing will harm you.
(20) However, do not rejoice that the spirits submit to you, but rejoice that your names are written in heaven.”
Likewise today, Christians are instructed to fight against evil spirits.
And these signs will accompany those who believe: In my name they will drive out demons;
For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.
In the book of Acts, the apostles (Acts 5:16), Philip (Acts 8:7) and Paul (Acts 16:16-18) are all specifically mentioned casting out evil spirits. The above sections of Scripture vividly show the contrast between the Old Testament and the New Testament. If evil spirits were really just agents for God acting out His will, then opposing them would be worse than hopeless, it would be sin. Furthermore, the New Testament portrays some evil spirits as having sinned so badly that they are now “in prison” awaiting the judgment (2 Pet. 2:4). God would have no cause to put these especially evil spirits in prison if they were only able to act with His permission in the first place, would He?
In the Old Testament, God is portrayed as killing both believers and unbelievers. But in the New Testament, Jesus calls the Devil a murderer (John 8:44), and Hebrews 2:14 says that it is the Devil who holds the power of death. Never, never, never in the New Testament is the death of a believer attributed to God.
 John Calvin, Institutes of the Christian Religion, Book 1, Editor: John T. McNeill (Westminster Press, Philadelphia, PA 1960), Pages 4-7. Calvin wrote, “From himself [Satan] and his own wickedness, therefore, arises his passionate and deliberate opposition to God. By this wickedness he is urged on to attempt courses of action which he believes to be most hostile to God. But because with the bridle of his power God holds him bound and restrained, he carries out only those things which have been divinely permitted to him; and so he obeys his Creator, whether he will or not, because he is compelled to yield him service wherever God impels him.” Of course, there are more than a few Christians who realize the truth that it is Satan, the Devil, God’s archenemy, who is responsible for most of the suffering that has plagued mankind since Adam’s original sin. But some, like Calvin, argue that Satan is merely playing a scapegoat role assigned to him by God. Others say that Satan must get permission from God before he can afflict people, but this also leaves God ultimately responsible for evil. Still others who acknowledge the existence of Satan teach that a Christian can avoid all suffering by walking in fellowship with God. This in part leads to the corresponding error that one’s human mind is in reality the cause of whatever comes upon him, good or bad. It also flatly contradicts God’s Word, which states that all those who live a godly life will suffer persecution (2 Timothy 3:12).