"witchcraft" and "dark magic" as the bible talks about it is related to magical works outside of God's provision. An exorcism that is done through the Lord is not performing dark magic at all, no more so than someone laying on hands to heal someone through prayer, etc. The casting out of the spirits is still God's work, through our hands.
this is how i differ between magic and psionics: if it involves asking the help of a demon, begging to certain creatures, praying to magical creatures, saying mantras, certain creatures, asking the help of a dead person magician than its magic. if its about your own abilities, willpower, self hypnosis, or asking the help of your greater self than its psionics.
God created a boundary between this world and the next world.
Anybody who dies in this world by the hands of Angel Israel, as commanded by God, is immediately reaped into the next world, and it is impossible to come back. Because this boundary of God is created by the Lord of the Worlds, whom possess all powers. Not even a spirit will be able to break it.
So since spirits do not exist in this materialistic world that was created by God...the practice of exorcism is contradictory to the powers of God.
If I am right, it is from God, if I am wrong, it is from myself.