You're creating a false dichotomy to try to force your beliefs into the argument. The idea of a soul is supernatural so the default naturalist/atheist position

You're creating a false dichotomy to try to force your beliefs into the argument. The idea of a soul is supernatural so the default naturalist/atheist position is to give it no more thought than unicorns or leprechauns (although this is not universally true; some believe in something analogous to a soul, but with far more complex reasoning than "God did it") in a meaningful debate. Instead the atheist/naturalist world view looks for other natural causes for consciousness and very easily finds them: the depth and breadth of complex phenomena emerging from smaller cells (chemical, biological, and informational) is astounding, so much so that we haven't even begin to scratch the surface of the neuroscience, let alone the complex phenomena that emerge from societies and an interconnected global civilization.