Adopt a Better Worldview!
Psyche means “soul.” The soul is the inner self, the non-material essence of the person. Unhappiness is the malady of the soul. Psychology is an old medicine dedicated to cure the unhappy soul.
By secular understanding, the psyche is an unidentifiable portion in the totality of a human being. It is a tremendous undertaking to deal with this obscure entity by science, so tremendous that no psychologist can face it squarely. Therefore, it seems a practical solution to ignore the psyche and go around it, as the builders of a road go around a huge, insurmountable mountain. Presently, psychologists cannot penetrate the nature of the soul, and they cannot cure it, but they try to cure the symptoms of unhappiness as they manifest themselves in the physical body.
The answer to the question posed in the title is that atheist philosophers and materialist scientists have snatched the psyche from psychology. They deny the existence of God; and consequently, they must deny the existence of the human soul, since God and the human soul are related. The soul is the conscious, self-knowing agent in the human being; it is identical to the unique person that is the spiritual Self. But does the identical self really exist? This is a classic question among philosophers.
The persuasion of scientific materialism denies the existence of everything outside the material realm, including the inner self, which is the spiritual essence of the person. Atheists, to be consistent in their philosophy, cannot admit that the Self (that is the Soul) inherently exists. It follows that atheists deny that the individual self is independent of a person’s history. Accordingly, they believe that the totality of the positive or negative impressions lodged in a person’s memory comprises what we call our “individual identity.”
Who Took The Psyche Out Of Psychology?