Acharya Prashant explains that an evil deed is not defined by a specific list of sins but is any action performed in a state of unconsciousness or lack of self-awareness. When one acts without consciousness, the mind is lost in external objects or past memories, leading to what is termed an evil deed. He clarifies that a wise person is beyond conventional ethics; their actions define ethics rather than being bound by a prescribed code of conduct. Even seemingly good acts, like helping others, are considered 'evil' if done in a state of unconsciousness because they lack the foundation of true understanding.