Why did God create Satan?
My understanding is that the angels existed, and Satan and his demons fell before the creation of heaven and earth.
Given the facts that there's no redemption for fallen angels, and God knew from the beginning that a third of his angels would fall, why did he create them in the first place? Or let them roam the earth instead of banishing them to hell right away?
Human sin is bad enough as it is, but through Satan's influence it becomes even worse.
My provisional understanding is that God uses Satan as a tool for salvation. If Satan had not entered Judas Iscariot (Luke 22:3), then Judas would not have betrayed Jesus, there would have been no crucifixion, and therefore no sacrifice for our sins.
But could God not have brought about Jesus' crucifixion in a different manner, without requiring Satan's " involuntary assistance"?