Since God is all-knowing, why would he create the angel of light, knowing that angel would become the devil?
Some might think that God is on the hook, in part, for the suffering in the world, because had he not created Lucifer, the “Angel of Light,” Lucifer never could have wrought the havoc on humanity that he has. Or some might think God was otherwise unloving in creating Lucifer, because had he not created him, Lucifer would not be enduring the pain of eternal separation from God. While those are understandable human reactions, they also reveal an imperfect understanding of what true love is.
First, God’s knowing something is going to happen—given his divine omniscience—doesn’t mean he’s going to cause something to happen. For example, we as mere humans still have our God-given free will in which we can choose to cooperate or not with God’s plan for humanity in general and for our lives in particular. God gives us free will to see whether we will trust him to provide what’s best for us or whether we’ll go our own way in opposition to him (see Matthew 25:31-46).
Here we see, then, that true love is not coercive. It respects the free will of the beloved. God doesn’t let sin and death have the last word either, sending his only begotten Son to become man and redeem us all through his one sacrifice of Calvary. So he gives us plenty of opportunities to repent and walk with him throughout our lives and to accept his gift of salvation and persevere in it.
Similarly, God undoubtedly created the devil and all of the other angels good and lovingly gave them the power to cooperate with his plan or to turn away from him. Sadly, the devil and other fallen angels perfectly foresaw that their rejection of God would mean their eternal separation from him, and yet they chose to turn away from God anyway. As a result, their rejection of God was not simply radical but irrevocable (CCC 392). And so the blame for their eternal destiny lies with them, not because of a lack of God’s mercy (Catechism 393). Because they basically said to God, “If this is heaven, to hell with it.”