The Open View of God might partially explain the mystery of sin and Satan. God is an optimist by nature, otherwise why create something to begin with if he didn't think it would turn out perfect and stay perfect. A perfect being, by definition, is only capable of optimism.
Can you imagine a being who knows everything that will ever occur? There are no surprises. He knows everything he will ever do and create and what will happen to his creation. God created the universe with the best of optimistic intentions. God had no idea when he created Lucifer that a ghastly creature like Satan would eventually emerge from Lucifer's free will and cause so much anti-perfection for millions (or thousands) of years. Otherwise why be partially responsible for such horror and evil?
If father or mother Hitler had received convincing proof from a time traveler that their little Adolf would murder so many innocent people, would they go ahead and play a role in allowing him to be born? They went ahead because they had no idea, of course. They hoped for the best and waited to see what would become of their little boy.
God, likewise, created Lucifer and his confederates, as well as humanity, with the best of intentions, hoping against hope that we'd all turn out as perfect as he would have liked for us all to have turned out.
Perhaps that's why he sent himself in the form of Christ, because in being partially responsible for allowing us to get into this mess as he was, he got himself into this mess as well, as one of us, to bare the brunt for having created us in the first place and to help us get out of it and return us to that hoped-for perfection he wished we all had chosen for ourselves all along. Think of the pain he's in to see how we all have suffered and continue to suffer. God wants this all to end as much as we do, otherwise he'd already have ended it for all concerned.
That, my friends, sounds like a responsible and sacrificing God and parent.