I've never claimed to know and I am repeating myself, but if you view this life as a simulation, and your spiritual life as reality, then what you do on Earth does not really have the same impact as if our lives on Earth was all there is.
So if you murder someone, are you damned forever? Well, if you believe in spirits, you just sent someone home. Could there be retribution? A solid maybe. The threat of punishment has always kept some percentage of spiritual people on the straight and narrow. Although personally I'd say it is an inferior reason to be good versus being good because it makes you a better you.
I say that if you believe in a system where spirits show up on Earth in flesh and blood and then cycle to the spiritual world you have to ask what is the purpose? If there is a purpose, there also could be a consequence. If you improve yourself, there may actually be a reward even if it is only self reward, being a better person. If you are an evil bastard, well who knows, what the consequences might be, but it is something worth pondering imo.