A Being exists through time, and undergoes transformations.
When a Man incarnates, the pre-existing spiritual Being transforms by a process including the organisation of 'solid matter', to incarnate as a zygote.
At death, the human Being leaves-behind solid matter and transforms to spirit.
With transformation of a being, the identity is maintained by provenance - i.e. by continued linear existence.
There is no retention of previous forms of organisation - so this is not a spirit getting matter added to it, or subtracted from it...
The reality is a continuously-existing-Being, transforming from a first spiritual entity into a solid entity (incarnation), then to a second and distinct spiritual entity.
It is the same Being throughout; because it has existed continuously, in unbroken continuity, through time.
Continuing from the schema above, the concept of transformation can also help us to understand what happens at resurrection.
Resurrection is a transformation of the spirit, when that spirit has been-through the prior transformation of mortal incarnation and death.
The human Being that is resurrected has, therefore, a lineage of transformations that include pre-mortal spirit, mortal incarnation, then post-mortal spirit.
The assumption is that only such a Being, with such a lineage, is able to be resurrected into an eternal divine incarnation.
(This is why Jesus needed to be born and to die, before he was resurrected.)
These descriptions can be regarded as a deeper explanation of my argument against computer AI.