Speculations

The soul is an algorithm. This algorithm takes a subjective world as input, and outputs the next subjective world. 

The persona is a diminished idea of the world processing algorithm focused on a particular set of states. These states are transient. Therefore rationally speaking it cannot be our identity.

The conscious being involves feeding the outputs of the algorithm back as the input of the algorithm. (Time is a side effect of this phenomenon.)

It is universally said that the purpose of us in the world is to learn. This is why we are limited in our ability to arbitrarily change either the inputs/outputs or the algorithm. We know from modern machine learning techniques that learning rates must be set to a small value, otherwise the model may overshoot and diverge. Therefore, although we have the ability to change things arbitrarily (aka “free will”), the effect of the change is very limited relatively speaking.

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This is tangential, but the existence of many souls processing the same (or roughly the same) world might be some kind of optimization. World building is probably quite computationally expensive, so going massively multi-agent running different threads of consciousness on the same world might be the sane way to do it. But then, it's always a bad idea to attribute limitations to "God"'s computational resources.