God did not create evil,
Lucifer was created as the highest angel and perfect "Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee."
and God created freewill the freewill to chose to serve God or rebel.
To show us God's true character and his principles in contrast to Satan's.
If Christ would have destroyed Satan at the onset of his rebellion we would have to be serving God in fear.
And this is not God wants he wants us to serve him by our choice not by force.