I believe that God may "allow" things to happen, even seemingly evil things. And we may not fully understand why he allowed those things. His thoughts are higher than our thoughts, and His way is higher than our ways. (Isaiah 55:8-9)
Discussion
Evil is instrumental to God's plan of bringing about an Elect people.
We don't understand exactly why that is the case, but we can discern that it is.
God is not "in a war" with evil, Man is.
Do you think that Satan would not cease to exist the second God wills it?
Therefor, Satan is instrumental to God's plan. That doesn't mean Satan is good, but that God's plan seems to require him for His plan for reasons He has not spelled out to us.
One can deduce that, God raising a truly concious and seperate Elect people to be Christ like after the end of this world, that a temporary existence of evil and Sin is necessary to that end.
Therefor, God authored evil into Creation, and is the author of evil.
May I ask if you're a Calvinist? I ask because I notice your belief seems to hold that God is the ultimate determiner of all things and that free will doesn't really exist. If so, I'd understand where you're coming from.
Yes, evil is not outside God's sovereignty. But I wouldn't say God "created" evil? I don't think that's the correct way to put it.
"Evil is designed by God."
-John MacArthur
"God didn't just permit evil, He ordained it."
-RC Sproul