“Mysticism” and “mystical experience” are terms so ambiguous that they require not only scrupulous precision in defining, but above all the development of a whole theory explaining their extensive denotation. The article aims to offer methodological guidelines for the development of the theory of mysticism, and at the same time draws attention to the aspects that should be thoroughly considered in order for the discourse on mysticism to be adequately treated. The content of this article is largely based on the thoughts of Bernard McGinn, a renowned American theologian and mystic theorist, who is undoubtedly considered one of the greatest experts on this subject. In his numerous publications, he focuses on a number of important aspects in mysticism, especially its religious context and processual character. Putting this issue in a broad perspective, the essence of mysticism is a direct experience of the Presence of God, which manifests itself in the language of a given culture. Thus, the traditionally recognized category of “mystical experience” turns out to be insufficient and obviously demands to be replaced with a more appropriate category of “mystical consciousness” or even “transpersonal meta-consciousness.”