I simply do not subscribe to either of these reductionist philosophies.
If Lewis defines materialism as you say: “the only thing that exists is matter or energy; that all things are composed of material and all phenomena (including consciousness) are the result of material interactions. In other words, matter is the only substance, and reality is identical with the actually occurring states of energy and matter,” then obviously he can savage the materialist position to the point of devastation, and so he should. The materialist description of reality is nonsense.
Similarly, Lewis’ positing of natural and “supernatural” realities is equally subject to devastating critique, the same critique that has been applied to every dualistic philosophy espoused since time began: dualism always fails because of it cannot account for the interaction problem.
That’s why I don’t subscribe to either extremist position. Neither is an efficient descriptor of reality, and thus is almost certainly not a true descriptor of reality.
That wasn’t Lewis’s definition, it was websters.
Supernaturalism is not dualistic. Supernaturalism posits that Mind has always existed and created nature, and holds nature in existence. The supernatural interacts with creation first by being the source of Reason, and secondly, though rarely, in the form of miracles (Judaism, Christianity, Islam). Deists believe in the supernatural but do not believe that it ever interferes with nature.
If naturalism/materialism and supernaturalism are both false then what is the third philosophical worldview?