I don’t mean to sound arrogant but you’re missing one crucial point. God is not a created being and he is not our father in the sense that you describe.

Our children can exist without us but since we all are created beings, we cannot have any meaningful existence without God beyond this world. Again, He is not our father he is our creator. He doesn’t need us, we need him for that simple fact.

Sure, we can make choices without Lucifer, but he serves the purpose of purifying the faithful in this life and provides fame wealth and power to those that follow him, for the same purpose. To also provide opposition in this life.