The basic principle is falsiability. It has been widely established that a sufficient condition to alter or eliminate consciousness and even personality traits is inflicting precise physical changes to the brain, such as severing pathways.
There is absolutely no evidence, let alone reproducible observations, supporting crackpot theories such as afterlifes or any form of consciousness that is not dictated by the brain.
It makes absolutely no sense to appeal to this or any other form of crackpot theories by alleging that established facts and knowledge covered by mainstream theories is still under development.