For we cannot throw out anything just because it contains the supernatural. We would have to throw out the Bible if we did.
Nor can we require that all supernatural elements be portrayed in a negative light. If we did, the Bible would again fail to meet that standard: God Himself is supernatural—He wouldn’t be God if He didn’t exceed the bounds of the natural. Also the pages of Scripture contain good angels, prophets who heal instantaneously and raise the dead, and objects that appear to have supernatural aspects, like the Ark of the Covenant.
Rather, we must discriminate between the power of God and the power which Satan and his minions wield. So what differentiates these two?
First, their power differs in how they can use it. The people serving God may be able to do miraculous things, but they can only use their power as God wills (compare Acts 14:8-10 with Philippians 2:25-27). But witches, sorcerers, and magicians use their power when they wish to fulfill their own desires. That’s why they can employ their powers for pay (e.g. Acts 16:16).
As a side note, whether people employ satanic power for good or bad doesn’t matter. Their desire to control through supernatural power shows a lack of submission to God, a distrust of His sovereignty, and an attempt to wrest power from Him. This is why there is no such thing as white magic; pride is the finite claiming superiority to the infinite. Therefore, God always condemns any power apart from Himself, whether obtained or consulted (Leviticus 20:27; Deuteronomy 18:10-12; Acts 13:6-11; Revelation 21:8).
Second, God’s power is superior. In Exodus 7:10-8:19 we read of a confrontation between Moses and Pharaoh’s magicians. While the magicians could duplicate three of the miracles (but only three), they couldn’t reverse God’s work. Instead they contributed to the death and destruction.
And ultimately, that is the main difference: Satanic power enslaves and destroys, while God’s power brings life. Prophets and apostles heal (e.g. Peter and the crippled man, Acts 3:1-10), but demons cause illness and handicaps (e.g. the demon-possessed blind-mute, Matthew 12:22). Similarly the false prophets make predictions, which lead to destruction (Jeremiah 23:30-40), while God’s prophets call for life-giving repentance (e.g. Ezekiel 18:30-32).