Exactly, the soul is something of the immaterial, having sentience means having a consciousness, but the one we're talking about is not some digital network with 0s and 1s, we're talking about something that goes beyond that and can never be copied, imitated sure, but not copied by robotics.

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I'm certain the Geth are self-aware, it is the driving reason why I always try to save them(before the destroy ending where I measure the weight of all decisions) but self aware is different from achieving true sentience and having a soul, a spirit, a consciousness that is part of the mind and independent of a physical body like a Geth unit or a server. We're getting into metaphysics here.

The tldr version is that to be sentient you must have a consciousness and to me doesn't include 0s and 1s, but true consciousness that comes from creation, the universe, a soul. Then again, who knows, maybe I could be wrong, since everything is energy, including consciousness, maybe there's a backdoor for AI to become truly sentient.