When you believe something is true which is not of God, you give an open invitation for others to compound your belief and thereby to abuse you.
Whenever you believe something of the ego, it gives permission to the entire ego thought system to come in and USE that belief against you. In essence, you've disowned your authority OVER the ego and instead have given authority TO the ego.
So lets say you have a 'weakness' in a certain area, where you believe that you don't deserve love. In that belief, you are agreeing with the ego. This means the ego now has free reign to act upon you 'through' that belief, having been given permission to do so BY your belief in it.
The same applies to 'sins', and this does have some parallels to Christianity... where when you believe you have sinned in some way, this opens the door you agreeing that you deserve punishment. It's not that other people believe this for you. YOU believe it against yourself. And you will HIRE other people and actively invite them to demonstrate how punishable you seem to be.
You want to suffer.
So if you don't want to suffer, there needs to be a 'repair' made in your mind, which corrects and undoes the ego belief, un-aligns you from giving permission to the ego, and aligns you with GOD.
When you are aligned with God, you have now given God permission to do whatever God does 'to you', i.e. heal you, love you, save you.