At each stage from separation through sin, guilt, fear, punishment and death, there is always some amount of projection of the cause of the problem.
When we believe in separation, i.e. sin, sin actually makes the separation unconscious, and then we are unaware of what caused sin. That which has no cause is considered to be a cause in its own right and not an effect. We will then go searching for the cause somewhere external, other than accepting that we caused it.
So we'll claim, I am sinful because God says I'm sinful, instead of that its because we chose to believe in separation.
Then at the next stage, feeling guilty, we won't just say I'm guilty because I sinned, we'll project the cause of the guilt outward and find an external cause for it. I'm guilty because someone else says so, or because society finds me guilty. Always someone else deciding that the guilt is true. And once again the guilt renders awareness of sin unconscious, so you go looking for reasons that caused the guilt.
This carries on down to fear, whereby even though guilt causes fear, fear makes guilt unconscious, and then you go looking for a projected cause for the fear. You start to claim that you are afraid "because of" all the external things or future things which are making you afraid. But none of these things are the cause of fear, your guilt is.
Then when punishment is happening, instead of admitting that you are punishing yourself, you'll be claiming that you are punished because someone or something else is punishing you. You'll look to all these reasons and causes why you are punished, other than that fear causes punishment.
And on it goes to death. Death is someone else's fault, happens by someone else's hand, is entirely out of your control, is not chosen by you at all etc. Punishment causes death but here you're claiming that death is caused by everything other than yourself.
Projection happens at all levels, because every level is an attempt to disown the level before it, and thus disown responsibility for choosing it. As soon as there is separation there is a cascade of irresponsibility and projection. It doesn't just happen once you get to guilt. It happens at every stage of separation all the way through to death.
These projections, these stories about who or what caused or justified the guilt or sin or fear etc, are defenses protecting the defenses. Guilt defends against sin, and the story that someone else found you guilty or you're guilty because of what you did to someone, is a defense that protects guilt from being undone. These fictions and stories have to be dismantled in order to look squarely at the problem, and then you can dismantle the problem itself.
The story about what caused the fear or the guilt or the sin is a cover-up story. Underneath it is your own belief that you are sinful guilty and afraid. Then these believes also are a cover-up story. Fear defends guilt, guilt defends sin, sin defends separation. Collapse these one at a time and you'll end up at the Atonement.