If God is omnipotent and knew that Lucifer would be the destruction of Mankind why would he create him? It sounds like God was trying to hurt his children more than help them.
Understanding this question as part of
"Why God, foreseeing that his creatures would use the gift of free will for their own injury, did not either abstain from creating them, or in some way safeguard their free will from misuse, or else deny them the gift altogether?"1
1. cf. Evil | New Advent.
The article Evil | New Advent, presents St. Thomas Aquinas' reply that
- God creates in absolute freedom and for his own purpose, which is to manifest his own goodness, power, and wisdom, and is pleased with the creatures themselves sharing in and reflecting his goodness.
- His creative act could not be free and be for him alone because if it depended "on the foreseen free act of any creature, God would thereby sacrifice His own freedom, and would submit Himself to His creatures, thus abdicating His essential supremacy - a thing which is, of course, utterly inconceivable."
- Free creatures, angels and men, attain their purpose and happiness by conforming themselves to the supreme purpose of creation, and encounter evil when they depart from it. That departure being the moral evil that angels and men introduce in creation.
The Catholic perspective is that God permits evil because he respects the freedom of his creatures and he can draw good from evil. Please see Catechism of the Catholic Church 309-314 especially 311-313 (sans footnotes)
311 Angels and men, as intelligent and free creatures, have to journey toward their ultimate destinies by their free choice and preferential love. They can therefore go astray. Indeed, they have sinned. Thus has moral evil, incommensurably more harmful than physical evil, entered the world. God is in no way, directly or indirectly, the cause of moral evil. He permits it, however, because he respects the freedom of his creatures and, mysteriously, knows how to derive good from it:
For almighty God. . ., because he is supremely good, would never allow any evil whatsoever to exist in his works if he were not so all-powerful and good as to cause good to emerge from evil itself.
312 In time we can discover that God in his almighty providence can bring a good from the consequences of an evil, even a moral evil, caused by his creatures: "It was not you", said Joseph to his brothers, "who sent me here, but God. . . You meant evil against me; but God meant it for good, to bring it about that many people should be kept alive." From the greatest moral evil ever committed - the rejection and murder of God's only Son, caused by the sins of all men - God, by his grace that "abounded all the more", brought the greatest of goods: the glorification of Christ and our redemption. But for all that, evil never becomes a good.
313 "We know that in everything God works for good for those who love him." The constant witness of the saints confirms this truth:
St. Catherine of Siena said to "those who are scandalized and rebel against what happens to them": "Everything comes from love, all is ordained for the salvation of man, God does nothing without this goal in mind."
St. Thomas More, shortly before his martyrdom, consoled his daughter: "Nothing can come but that that God wills. And I make me very sure that whatsoever that be, seem it never so bad in sight, it shall indeed be the best."
Dame Julian of Norwich: "Here I was taught by the grace of God that I should steadfastly keep me in the faith. . . and that at the same time I should take my stand on and earnestly believe in what our Lord shewed in this time - that 'all manner [of] thing shall be well.'"