Modern Christian mythology is a mashup of a lot of things. A scholar would be required to really unpack a lot of it, but consider that much of what we think of as lore, motivation, and character are newer additions. Dante’s Inferno probably has more influence on our ideas about Lucifer and Hell than the Bible.

Once you start unpacking these old stories with a post-modern mindset, the logic of it quickly stops making sense.

A modern Christian might opine that Lucifer is a prisoner of Hell but not a genuine threat to the power of their Almighty God. He’s not awarded this position. He’s lost God’s grace and dwells outside of his love - the worst punishment imaginable in the mind of some Christians.