It's not a matter of belief, it is a matter of demonstrable fact that some criminals are capable of completely reforming. To deny this is simply to deny reality.
(It is also clearly apparent that some criminals are unreformable - telling the difference a priori remains the hard part).
Joking aside, I think that using prisons just for isolation is a waste of tax payer money.
Just think about at the case at hand, we are wasting the money needed to keep this guy in jail for another 8 decades with no actual reasons.
edit: fix grammar