Actually, the answer is in The Word.
Satan and his gang are a necessity in the Grand Plan.
We need Satan and his cohorts to help us learn the meaning of bad.
Satan only does what he is permitted to do for our benefit.
It will all be very clear when the time comes to have our eyes opened and our ears unstopped.
For Our Father and His Son all things are possible. Everything is under control.
We must experience this Earthly travail in order to choose.
In the end all will be made good.