Abstract
This paper examines the epistemological, ontological and mystical aspects of St. Augustine's thought, showing how his reflection on faith, religious experience and cognition shapes a coherent vision of the human relationship with God. The central theme is the search for the light of truth, which, in Augustine's view, involves both intellectual speculation and profound spiritual experience. The conception of cognition encompasses rational analysis and inner illumination in the space of religiosity. Augustine’s piety grows from his personal journey of conversion, following the maxim: „Interior intimo meo et superior summo meo (Confessiones, III, 6, 11)”. A particular phenomenology of spirituality emerges in the philosopher's writings, combining elements of St Paul's theology, Neoplatonism and the Christian tradition of asceticism and contemplation. Central to this is the commandment of love, which constitutes both the path to mystical union with God and the ethical foundation of spiritual life. Augustine emphasises that full knowledge of God is only possible through grace and inner enlightenment. The paper explores the theory of illumination as a key element of Augustinian gnoseology and the relationship between cognition and being, presenting two main interpretative currents: one emphasising the transcendental nature of divine illumination, the other the inner search for truth as participation in transcendent reality. Augustine’s anthropological-cognitive triad, pointing to the relationship between cognition and existence, is examined in the context of his epistemology and ontology. Illumination is presented as a conscious process where reason plays a key role. The final section presents Augustine’s ontological perspective, where the unity of thought, being, and existence reveals the relationship between cognition and existence, while leaving open the possibility of fully understanding God in ontological terms. Ultimately, the juxtaposition of Augustine's spiritual experiences offers a deeper understanding of his theology as a dynamic synthesis of life, faith and also Christian prayer.