Its not a belief. Your consciousness is formed by the synapses in your brain, and when you're sick, dying or just on drugs you can lose sense of self. I've had friends and family suffer because of this to the point of being different people, committing suicide or in my friends case his dad pulled the plug on himself when my friend was about 13. I've experienced psychosis myself and it fucking sucks to feel how fragile your means of processing reality really are.
Basically the idea that you get another chance goes against life being this fleeting and precious existence and instead of treating others with that kind of respect its only a tool people have used to offer useless thoughts and prayers to the deceased posthumous, or like i've experienced being told that im "going to hell" for things I can't help.
I'm sorry that stuff happened to you and nobody should tell you you're going to hell for things you can't help. But it is a belief.
I also know others who have suffered from mental illness, and have even suffered from it myself, and I find it comforting to know I'm more than my brain. A soul, to me, is more powerful than a brain.
I understand why you're being so defensive but it isn't what I believe.