Zombies are logically possible. That is, we can conceive of them. They aren’t like square circles. Philosophical zombies are human bodies that look and act just like we do, but have no experiences, no inner world. They aren’t conscious in this sense. They will tell you they are conscious if asked, by the way. For their brain circuits are sufficient for this and any other human behavior.
A world that has complex organisms that do what we do yet lack consciousness is possible. If so, then consciousness is an added feature to a material world. All of our survival can be explained purely in terms the evolution of mechanisms, without mentioning inner experience even once. Consciousness, defined strictly as inner experience, doesn’t have a real explanatory role.
Thus the philosopher David Chalmers thinks that consciousness is a primitive. It may be a basic feature of the universe, or at least as basic as matter and energy. It doesn’t seem explainable in terms of them. (For more about zombies and materialism, see this blog post from Phillip Goff. For more about the troubles of explaining consciousness, see this blog by Bobby Azarian).
“What does this have to do with God?” you might ask. Well, if there is something more than what physics studies (the material universe), that might open the door for immaterial beings like God. Moreover, given that there is no physical explanation for consciousness, and if it also is a primitive, then consciousness could only come from consciousness. And since God is an always existing conscious being, God could be an explanation for consciousness.
This wouldn’t be enough for a case for God: for one could just say that our consciousness derives from some general consciousness woven throughout the universe, and didn’t come from a particular conscious being. There is additional evidence for God, however, this evidence is problematic to skeptics. But one reason it is problematic may be disarmed by the mystery of consciousness.
The problematic evidence: consider the Kalam Cosmological Argument: The universe had a beginning, and things with beginnings have causes. Therefore, something caused the universe. That something must be outside the universe, and that something isn’t material (otherwise it would be part of the universe). Add to this that other features of the universe, such as the fine-tuning of physical constants for life, seem designed. Perhaps the cause of the universe is an immaterial mind.
The problem with the problematic evidence: we know that many features of our minds depend on physical brains. But there was no cosmic brain existing before the universe! Postulating such a being as an explanation for the universe is ridiculous, as Richard Dawkins argues, for a God like this would have be immensely complex and improbable.
How consciousness helps: Consciousness seems inexplicable in terms of brains. This opens up the possibility of a non-physical explanation. And, for all we know, there might be non-physical ways in which to instantiate other parts of the mind. So there could be such things as minds without problematically complex brains. And these ways, even if complex, might not contribute to improbability like physical complexity does (e.g., even complex mathematical statements are no less probable than simple ones). Thus God may not be such a long shot as Dawkins and others suppose.
It is a bit speculative to speak of such things; but regarding the beginning of the universe, and the fine tuning of the physical constants, it’s no more speculative than any of the other hypotheses floating around (especially the multiverse hypothesis). This, plus the fact that perhaps the most important part of mind can’t be explained purely in terms of physics fits better with this hypothesis than with atheistic naturalism. For not only could God create matter, He can create mind as well. Not so for multiverses. All a multiverse could do is create zombies.