The article analyzes the spiritual-mystical components underlying speech, language and self-consciousness of a person. The research is carried out on the basis of an interdisciplinary scientific approach. The main attention is focused on the prologue of St. John, considered as a scientific theorem that paves the way for solving the problem of the existence of language and human self-consciousness. The methodological basis of the study is the author's concept of the formation of a sign-symbol of a mystical, disembodied being – a spirit, which formed the basis of a face symbol, in the phylogeny of humanity, as a consequence of mental mechanisms of transfer and replacement. This concept is used for the first time in the aspect of comprehending the prologue of St. John, which is the novelty of the study. The work logically substantiates the impossibility of the existence of the human word, and at the same time of abstract thinking and self-consciousness, without the psychic reality of an incorporeal, mystical controller and verbal designer of thought – namely, the spirit that prompts the subject to incessant acts of identification with him. At the same time, the logic of the study allows us to draw a conclusion about the scientific truth of the prologue of St. John, with regard to the beginning of human language and self-consciousness. Also, as a conclusion, the author emphasizes the key importance of a religious belief in a mystical ruler for the realization of the existence of language and self-consciousness of a person.