Is God willing to prevent evil, but not able, then he is not omnipotent
It is man who must end evil and can be done only through Christ. Since so few believe, ergo evil.
Is he able but not willing? Then he is manevolent.
Only man causes evil. Since all good comes through God, a storm that kills many is not an evil thing, you may not like it but to eternity it is of no consequence. Your eternal soul on the other hand has consequense.