This study examines the issue of knowledge and truth in Theophilos Kairis, whose point of view is bounded from Christianity that substitutes but also borrows elements from the ancient religion, from Enlightenment, which stands radically opposed to conservatism, and elements from reverence known as theosebism, meaning «soul that tends to the divine». Especially, the cognitive state of man serves the function of three factors: God (the reason of knowledge-gnosis), the Soul (its source) and Man (his needs work as the triggers). This way follows the path from the simple elements of cognition (ideas and concepts) to internal emotions and lately the complicated concepts and the truth itself. However, all this procedure obeys the ultimate criterion of logos which is existential as the structure of knowledge and truth. Similarly, the science, as knowledge of absolute knowledge, is a series of truths proven, that is based on a self-evident principle, method and assumes a theory, which by the way and consequently is based and founded in Logos. Kairis does not limit himself to a philosophical rationalism but also follows a foundation of empirical research and the laws of nature and society. Consequently, knowledge and truth as its results consists of the combination of natural and social laws and logical processes, although he, exceptionally, does not avoid revelation at all.