Though influenced by Satan and the world, sin is still a personal choice. Christ's sacrifice and God's Spirit provide our only defense against its pulls.
We cannot assume that angels are immortal and share the same kind of spirit God Almighty has; we cannot assume they are indestructible.
Why is human nature so corrupt? Why is it so widespread? How did it come to be? Did God create it this way?
Our fear of being judged negatively by God should spur us to greater obedience and growth toward godliness. The fear of God is a fundamental mindset.