This presentation aims to focus on Montessori's approach to religious education, with particular attention to the spiritual formation of teachers ("a synthesis of the scientist and the mystic") and to "educational sins". Drawing on some of Maria Montessori's writings and experiences inspired by the method, the presentation will explore the relationship between the development of a scientific pedagogy on the one hand and the spiritual and religious vision on the other; it will also examine the importance of "means of psychic development" as the basis for inner development and the spiritual growth of the child.